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{{Short description|Decentralized digital currency}} | |||
{{Use dmy dates|date=December 2013}} | |||
{{for|the colloquial expression for coinage|Bit (money)}} | |||
{{Infobox currency | |||
{{Redirect-distinguish-text|₿|"฿" for ]}} | |||
| image_1 = Bitcoin logo.svg | |||
{{pp-extended|small=yes}} | |||
| image_title_1 = logo of the bitcoin reference client | |||
{{Use dmy dates|date=March 2024}} | |||
| issuing_authority = ]{{refn | group = note | Bitcoin does not have a ].<ref name="JSC" />}} | |||
{{Use American English|date=December 2017}} | |||
| issuing_authority_title = Administration | |||
{{infobox cryptocurrency | |||
| date_of_introduction = {{Start date and age|df=yes|2009|1|3}} | |||
| currency_name = Bitcoin | |||
| using_countries = worldwide | |||
| image_1 = Bitcoin.svg | |||
| inflation_title = ] | |||
| image_2 = | |||
| inflation_rate = 25 bitcoins per block (approximately every ten minutes) until mid 2016,<ref name=quantitative>{{cite web | title = Quantitative Analysis of the Full Bitcoin Transaction Graph | url = http://eprint.iacr.org/2012/584.pdf | publisher = Cryptology ePrint Archive | accessdate = 18 October 2012 | author = Ron Dorit | author2 = Adi Shamir | year=2012}}</ref> and then afterwards 12.5 bitcoins per block for 4 years until next halving. This halving continues until 2110-2140 when 21 million bitcoins have been issued. | |||
| image_width_1 = 150 | |||
| inflation_source_date = | |||
| image_width_2 = 110 | |||
| subunit_ratio_3 = {{val|e=-8}} | |||
| image_title_1 = Official logo from bitcoin.org | |||
| subunit_name_3 = satoshi<ref name="satoshi unit">{{cite web | title = Cracking the Bitcoin: Digging Into a $131M USD Virtual Currency | url = http://www.dailytech.com/Cracking+the+Bitcoin+Digging+Into+a+131M+USD+Virtual+Currency/article21878.htm | author = Jason Mick | publisher = Daily Tech | date = 12 June 2011 | accessdate = 30 September 2012 | deadurl = no}}</ref> | |||
| alt1 = Prevailing bitcoin logo | |||
| subunit_ratio_2 = {{val|e=-6}} | |||
| precision = 10<sup>−8</sup> | |||
| subunit_name_2 = microbitcoin | |||
| subunit_ratio_1 = {{frac|1000}} | |||
| symbol_subunit_2 = μBTC | |||
| subunit_name_1 = Millibitcoin | |||
| subunit_ratio_1 = {{val|e=-3}} | |||
| subunit_ratio_2 = {{frac|{{val|1000000}}}} | |||
| subunit_name_1 = millibitcoin | |||
| subunit_name_2 = Microbitcoin | |||
| symbol_subunit_1 = mBTC | |||
| subunit_ratio_3 = {{frac|{{val|100000000}}}} | |||
| symbol = BTC,{{refn | group = note | name = BTCcode | {{as of | 2014}}, BTC is the most commonly used code.<ref name = "standardize">{{cite web | publisher = ] | author = Lauren Orsini | date = 8 October 2014 | accessdate = 2 November 2014 | title = Look Out—Bitcoin Wants To Get Standardized | url = http://readwrite.com/2014/10/08/bitcoin-foundation-standardize-currency}}</ref>}} XBT,{{refn | group = note | name = XBTcode | {{as of | 2014}}, XBT is used by ],<ref>{{cite news | title = Bitcoin Ticker Available On Bloomberg Terminal For Employees | publisher = ] | url = http://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ | date = 9 August 2013 | author = Romain Dillet | accessdate = 2 November 2014}}</ref> ],<ref>{{cite web | title = Bitcoin Composite Quote (XBT) | url = http://money.cnn.com/quote/quote.html?symb=XBT | publisher = CNN | work = CNN Money | accessdate = 2 November 2014}}</ref> and ].<ref>{{cite web | title = XBT - Bitcoin | publisher = xe.com | accessdate = 2 November 2014 | url = http://www.xe.com/currency/xbt-bitcoin?}}</ref>}} {{nowrap|]}}{{refn | group = note | name = BTCsym | Bitcoin Foundation will attempt to establish a Unicode symbol for bitcoin. The leading candidates are B⃦ (letter B with combining double vertical stroke overlay), ฿ (the Thai Baht symbol), and Ƀ (]).<ref name="standardize" />}} | |||
| subunit_name_3 = {{lang|ja-Latn|Satoshi|italic=no}}{{efn|name=satoshi}}<ref name="satoshi unit">{{Cite journal |last=Bradbury |first=Danny |date=November 2013 |title=The problem with Bitcoin |url=https://linkinghub.elsevier.com/retrieve/pii/S1361372313701015 |journal=Computer Fraud & Security |language=en |volume=2013 |issue=11 |pages=5–8 |doi=10.1016/S1361-3723(13)70101-5 |access-date=25 November 2023 |archive-date=18 January 2023 |archive-url=https://web.archive.org/web/20230118052355/https://linkinghub.elsevier.com/retrieve/pii/S1361372313701015 |url-status=live |issn=1361-3723}}</ref> | |||
| used_coins = unspent outputs of transactions denominated in any multiple of satoshis<ref name="Antonopoulos2014">{{cite book | author = Andreas M. Antonopoulos | date = April 2014 | url = http://chimera.labs.oreilly.com/books/1234000001802/ch02.html | chapter = 2 | publisher = O'Reilly Media | accessdate = 23 October 2014 | title = Mastering Bitcoin. Unlocking Digital Crypto-Currencies}}</ref> | |||
| plural = Bitcoins | |||
| symbol = '''₿'''<br/>(Unicode: {{unichar|20BF|BITCOIN SIGN|html=}})<ref name="unicode-10">{{cite web |date=20 June 2017 |title=Unicode 10.0.0 |url=https://www.unicode.org/versions/Unicode10.0.0/ |url-status=live |archive-url=https://web.archive.org/web/20170620130342/http://www.unicode.org/versions/Unicode10.0.0/ |archive-date=20 June 2017 |access-date=20 June 2017 |publisher=Unicode Consortium}}</ref> | |||
| code = BTC | |||
| implementations = ] | |||
| initial_release_version = 0.1.0 | |||
| initial_release_date = {{Start date and age|df=yes|2009|1|9|p=y}} | |||
| code_repository = {{URL|https://github.com/bitcoin/bitcoin}} | |||
| status = Active | |||
| latest_release_version = 28.0 | |||
| latest_release_date = {{Start date and age|df=yes|2024|10|04|p=y}}<ref>{{cite web |title=Bitcoin Core 28.0 released |date=2 October 2024 |url=https://bitcoincore.org/en/2024/10/02/release-28.0/ |access-date=5 October 2024 |archive-date=5 October 2024 |archive-url=https://web.archive.org/web/20241005063435/https://bitcoincore.org/en/2024/10/02/release-28.0/ |url-status=live}}</ref> | |||
| forked_from = | |||
| website = {{URL|https://bitcoin.org}} | |||
| programming_languages = C++ | |||
| operating_system = | |||
| author = ] | |||
| developer = | |||
| white_paper = | |||
| source_model = ] | |||
| license = ] | |||
| ledger_start = {{Start date and age|df=yes|2009|1|3|p=y}} | |||
| hash_function = ] (two rounds) | |||
| circulating_supply = ₿19,591,231 ({{as of|2024|01|06|lc=y}}) | |||
| supply_limit = ₿21,000,000{{efn|name=supply}} | |||
| timestamping = ] (partial hash inversion) | |||
| issuance_schedule = Decentralized (block reward)<br />Initially ₿50 per block, halved every 210,000 blocks | |||
| block_time = 10 minutes | |||
| block_reward = ₿3.125 ({{as of|2024|lc=y}}) | |||
| exchange_rate = Floating | |||
| market_cap = <!--A reliable source is required --> | |||
| using_countries = ]<ref name="BTCSVSept7FT">{{cite news |title=El Salvador's dangerous gamble on bitcoin |url=https://www.ft.com/content/c257a925-c864-4495-9149-d8956d786310 |date=7 September 2021 |access-date=7 September 2021 |work=] |department=The editorial board |archive-date=7 September 2021 |archive-url=https://web.archive.org/web/20210907081627/https://www.ft.com/content/c257a925-c864-4495-9149-d8956d786310 |url-status=live }}</ref> | |||
}} | }} | ||
{{Special characters}} | {{Special characters}} | ||
'''Bitcoin''' (abbreviation: '''BTC'''; ]: '''₿''') is the first ] ]. Based on a ] ideology, bitcoin was invented in 2008 by ], an unknown person.<ref name="whoissn">{{Cite news |last=S. |first=L. |date=2 November 2015 |title=Who is Satoshi Nakamoto? |newspaper=The Economist |url=https://www.economist.com/the-economist-explains/2015/11/02/who-is-satoshi-nakamoto |access-date=21 November 2023 |archive-date=22 November 2020 |archive-url=https://web.archive.org/web/20201122172929/https://www.economist.com/the-economist-explains/2015/11/02/who-is-satoshi-nakamoto |url-status=live }}</ref> Use of bitcoin as a ] began in 2009,<ref name="NY2011">{{Cite magazine |last=Davis |first=Joshua |date=10 October 2011 |title=The Crypto-Currency: Bitcoin and its mysterious inventor |url=https://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |url-status=live |archive-url=https://web.archive.org/web/20141101014157/http://www.newyorker.com/magazine/2011/10/10/the-crypto-currency |archive-date=1 November 2014 |access-date=31 October 2014 |magazine=]}}</ref> with the release of its ].<ref name="Antonopoulos2014">{{Cite book |last=Antonopoulos |first=Andreas M. |title=Mastering Bitcoin: Unlocking Digital Crypto-Currencies |year=2014 |publisher=O'Reilly Media |isbn=978-1-4493-7404-4 |author-link=Andreas Antonopoulos}}</ref>{{rp|ch. 1}} In 2021, ].<ref name="BTCSVSept7FT" /> It is mostly seen as an ] and has been described by some scholars as an ].<ref name="4Nobels">{{Cite news |last=Wolff-Mann |first=Ethan |date=27 April 2018 |title='Only good for drug dealers': More Nobel prize winners snub bitcoin |work=Yahoo Finance |url=https://finance.yahoo.com/news/good-drug-dealers-nobel-prize-winners-snub-bitcoin-184903784.html |url-status=live |access-date=7 June 2018 |archive-url=https://web.archive.org/web/20180612141128/https://finance.yahoo.com/news/good-drug-dealers-nobel-prize-winners-snub-bitcoin-184903784.html |archive-date=12 June 2018}}</ref> As bitcoin is ]ous, ] has attracted the attention of regulators, leading to ] {{as of|2021|lc=yes}}.<ref name="SunYin2019">{{Cite journal |last1=Sun Yin |first1=Hao Hua |last2=Langenheldt |first2=Klaus |last3=Harlev |first3=Mikkel |last4=Mukkamala |first4=Raghava Rao |last5=Vatrapu |first5=Ravi |date=2 January 2019 |title=Regulating Cryptocurrencies: A Supervised Machine Learning Approach to De-Anonymizing the Bitcoin Blockchain |url=https://www.researchgate.net/publication/332118587 |journal=] |language=en |volume=36 |issue=1 |page=65 |doi=10.1080/07421222.2018.1550550 |s2cid=132398387 |issn=0742-1222 |access-date=29 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113631/https://www.researchgate.net/publication/332118587_Regulating_Cryptocurrencies_A_Supervised_Machine_Learning_Approach_to_De-Anonymizing_the_Bitcoin_Blockchain |url-status=live }}</ref> | |||
] in the ] ] verify transactions through ] and record them in a public ], called a ], without central oversight. ] between nodes is achieved using a computationally intensive process based on ], called ], that secures the bitcoin blockchain. Mining consumes large quantities of electricity and has been criticized for ].<ref>{{Cite news |last1=Huang |first1=Jon |last2=O’Neill |first2=Claire |last3=Tabuchi |first3=Hiroko |author3-link=Hiroko Tabuchi |date=3 September 2021 |title=Bitcoin Uses More Electricity Than Many Countries. How Is That Possible? |url=https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |url-status=live |archive-url=https://web.archive.org/web/20230217105559/https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |archive-date=17 February 2023 |access-date=26 October 2022 |work=The New York Times |language=en-US |issn=0362-4331}}</ref> | |||
'''Bitcoin''' is a software-based online ] described by ]<ref group="note" name="Satoshi">It is not known whether the name ''Satoshi Nakamoto'' is real or a pseudonym, or whether it represents one person or a group of people.</ref> in 2008<ref name="paper">{{cite web|url= https://bitcoin.org/bitcoin.pdf |title= Bitcoin: A Peer-to-Peer Electronic Cash System |date= October 2008 |publisher= bitcoin.org |accessdate= 28 April 2014}}</ref> and introduced as ] in 2009.<ref>{{cite web | last = Davis | first = Joshua | title = The Crypto-Currency: Bitcoin and its mysterious inventor | url = http://www.newyorker.com/reporting/2011/10/10/111010fa_fact_davis | work = The New Yorker | date = 10 October 2011 | accessdate = 31 October 2014}}</ref> Payments are recorded in a public ] using its own ],<ref name=btcregs /> which is also called '''bitcoin'''.{{refn | group = note | There is no uniform convention for ''bitcoin'' capitalization. Some sources use ''Bitcoin'', capitalized, to refer to the ] and ] and ''bitcoin'', lowercase, to refer to the unit of account.<ref name="capitalization">{{cite web | url = http://www.newyorker.com/online/blogs/elements/2013/04/the-future-of-bitcoin.html | title = The Bitcoin Boom | publisher = Condé Nast | work = The New Yorker | date = 2 April 2013 | accessdate = 22 December 2013 | author = Bustillos, Maria | quote = Standards vary, but there seems to be a consensus forming around Bitcoin, capitalized, for the system, the software, and the network it runs on, and bitcoin, lowercase, for the currency itself.}}</ref> The ]<ref>{{cite news|last= Vigna |first= Paul |title= BitBeat: Is It Bitcoin, or bitcoin? The Orthography of the Cryptography |url= http://blogs.wsj.com/moneybeat/2014/03/14/bitbeat-is-it-bitcoin-or-bitcoin-the-orthography-of-the-cryptography |accessdate= 21 April 2014 |newspaper= ] |date=3 March 2014}}</ref> and ]<ref>{{cite web|publisher= The Chronicle of Higher Education (chronicle.com) |title= The latest style |date= 14 April 2014 |last= Metcalf |first= Allan |series= Lingua Franca blog |url= http://chronicle.com/blogs/linguafranca/2014/04/11/the-latest-style/ |accessdate= 19 April 2014}}</ref> advocate use of lowercase ''bitcoin'' in all cases, however. This article follows the latter convention.}} Payments work ] without a central repository or single administrator, which has led the ] to call bitcoin a decentralized ].<ref name="JSC">{{cite web|url= http://www.fincen.gov/news_room/testimony/html/20131119.html |title= Statement of Jennifer Shasky Calvery, Director Financial Crimes Enforcement Network United States Department of the Treasury Before the United States Senate Committee on Banking, Housing, and Urban Affairs Subcommittee on National Security and International Trade and Finance Subcommittee on Economic Policy |publisher= Financial Crimes Enforcement Network |work= fincen.gov |date= 19 November 2013 |accessdate= 1 June 2014}}</ref> Although its status as a currency is disputed, media reports often refer to bitcoin as a ] or ].<ref name="currencydispute"/> Bitcoin is the first fully implemented decentralized cryptocurrency; most other cryptocurrencies are similar and derived from it. It is also the largest cryptocurrency in terms of total market value.<ref>{{cite news | last = Espinoza | first = Javier | title = Is It Time to Invest in Bitcoin? Cryptocurrencies Are Highly Volatile, but Some Say They Are Worth It | date = 22 September 2014 | url = http://online.wsj.com/articles/how-to-decipher-cryptocurrencies-1411333011 | work = Journal Reports | publisher = ] | accessdate = 3 November 2014}}</ref> | |||
{{TOC LIMIT|4}} | |||
Bitcoins are created as a reward for processing work in which users offer their computing power to verify and record payments into the public ledger. This activity is called ''mining'', which individuals or companies engage in, in exchange for transaction fees and newly created bitcoins.<ref name="primer">{{cite web | url=http://mercatus.org/sites/default/files/Brito_BitcoinPrimer.pdf | title=Bitcoin: A Primer for Policymakers | publisher=George Mason University | work=Mercatus Center | year=2013 | accessdate=22 October 2013 | author=Jerry Brito and Andrea Castillo}}</ref> Besides mining, bitcoins can be obtained in exchange for ], products, and services.<ref name="bitpay130916" /> Users can send and receive bitcoins electronically for an optional transaction fee<ref name="EconOfBTC">{{cite web | url=http://www.weis2013.econinfosec.org/papers/KrollDaveyFeltenWEIS2013.pdf | title=The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries | work=The Twelfth Workshop on the Economics of Information Security (WEIS 2013) | |||
| date= 11–12 June 2013 | accessdate=8 May 2014 | author=Joshua A. Kroll, Ian C. Davey, Edward W. Felten | |||
| quote="If the value paid out of a transaction (in Bitcoins) is less than the amount put in, the difference is treated as a transaction fee that can be collected by whoever manages to mine a block containing that transaction. A transaction fee is like a tip or gratuity left for the miner."}}</ref> using ] on a ], ], or a ]. | |||
==History== | |||
Bitcoin as a form of payment for products and services has seen growth,<ref name="bitpay130916">{{cite web | url = http://techcrunch.com/2013/09/16/bitpay-10000-merchants/ | title = BitPay Passes 10,000 Bitcoin-Accepting Merchants On Its Payment Processing Network | author = Natasha Lomas | publisher = Techcrunch.com | work = Techcrunch | date = 16 September 2013 | accessdate = 21 October 2013}}</ref> and merchants have an incentive to accept the digital currency because ]s are lower than the 2–3% typically imposed by ] processors.<ref name="merchantfee">{{cite news | url=http://www.nytimes.com/2013/10/31/technology/bitcoin-pursues-the-mainstream.html?_r=0 | title=Bitcoin Pursues the Mainstream | work=The New York Times | date=30 October 2013 | accessdate=4 November 2013 | author=Wingfield, Nick}}</ref> The ] has warned that bitcoin lacks consumer protections.<ref name="ebawarn"/> Unlike credit cards, any fees are paid by the purchaser, not the vendor. Bitcoins can be stolen<ref>{{cite news|url=http://dealbook.nytimes.com/2013/12/05/in-the-murky-world-of-bitcoin-fraud-is-quicker-than-the-law/?ref=business&_r=1 |title=In the Murky World of Bitcoin, Fraud Is Quicker Than the Law |publisher=''The New York Times'' |author=Nathaniel Popper| date=5 December 2013| accessdate=12 December 2013}}</ref> and ]s are impossible.<ref name="primer" /> {{As of|2013|July}} the commercial use of bitcoin was small compared to its use by ], which has contributed to price volatility.<ref name=winkles>{{cite news | url=http://blogs.wsj.com/moneybeat/2013/07/02/beware-the-risks-of-the-bitcoin-winklevii-outline-the-downside/ | title=Beware the Risks of the Bitcoin: Winklevii Outline the Downside | publisher=''The Wall Street Journal'' | work=Moneybeat | date=2 July 2013 | accessdate=21 October 2013 | author=Grocer, Stephen}}</ref> | |||
{{Main|History of bitcoin}} | |||
===Background=== | |||
Bitcoin has been a subject of scrutiny amid concerns that it can be used for illegal activities.<ref>{{cite news | url = http://blogs.wsj.com/washwire/2013/11/05/bitcoin-comes-under-senate-scrutiny/ | title = Bitcoin Comes Under Senate Scrutiny | date = 5 November 2013 | first = Ryan | last = Tracy | work = The Wall Street Journal | accessdate = 31 October 2014}}</ref> Bitcoins are used to purchase illicit items{{refn | group = note | name = illegal | Bitcoin facilitates illegal trading like USD, gold, etc. It is like cash in facilitating illegal trades. The difference is that bitcoin transaction history is publicly available, while cash transaction history is not. Bitcoin also facilitates ''legal'' trading.<ref name="Andolfatto2014-03" />}} at ] black markets and are seized by authorities when such sites are shut down. | |||
Before bitcoin, several ] were released, starting with ]'s ] in the 1980s.<ref name=Narayanan2017/> The idea that solutions to computational puzzles could have some value was first proposed by cryptographers ] and ] in 1992.<ref>{{Citation |last=Dwork |first=Cynthia |title=Pricing via Processing or Combatting Junk Mail |date=1993 |work=Advances in Cryptology — CRYPTO’ 92 |volume=740 |pages=139–147 |editor-last=Brickell |editor-first=Ernest F. |url=http://link.springer.com/10.1007/3-540-48071-4_10 |access-date=2025-01-02 |place=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |language=en |doi=10.1007/3-540-48071-4_10 |isbn=978-3-540-57340-1 |last2=Naor |first2=Moni}}</ref><ref name=Narayanan2017/> The concept was ] by ] who developed ], a ] scheme for ] in 1997.<ref name="Narayanan2017" /> The first proposals for distributed digital scarcity-based ] came from ]s ] (b-money) and ] (]) in 1998.<ref>{{Cite journal |last1=Tschorsch |first1=Florian |last2=Scheuermann |first2=Bjorn |date=2 March 2016 |title=Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies |url=https://ieeexplore.ieee.org/document/7423672 |journal=IEEE Communications Surveys & Tutorials |volume=18 |issue=3 |pages=2084–2123 |doi=10.1109/COMST.2016.2535718 |s2cid=5115101 |issn=1553-877X |access-date=23 November 2023 |archive-date=19 November 2023 |archive-url=https://web.archive.org/web/20231119025114/http://ieeexplore.ieee.org/document/7423672 |url-status=live }}</ref> In 2004, ] developed the first currency based on reusable proof of work.<ref>{{cite book |last1=Judmayer |first1=Aljosha |chapter=History of Cryptographic Currencies |date=2017 |chapter-url=https://link.springer.com/10.1007/978-3-031-02352-1_3 |title=Blocks and Chains |pages=15–18 |publisher=] |language=en |doi=10.1007/978-3-031-02352-1_3 |isbn=978-3-031-01224-2 |last2=Stifter |first2=Nicholas |last3=Krombholz |first3=Katharina |last4=Weippl |first4=Edgar |series=Synthesis Lectures on Information Security, Privacy, and Trust |url=https://link.springer.com/book/10.1007/978-3-031-02352-1 |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122135006/https://link.springer.com/book/10.1007/978-3-031-02352-1 |url-status=live }}</ref> These various attempts were not successful:<ref name="Narayanan2017" /> Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against ], while b-money and bit gold were not resistant to ]s.<ref name=Narayanan2017>{{Cite journal |last1=Narayanan |first1=Arvind |last2=Clark |first2=Jeremy |date=27 November 2017 |title=Bitcoin's academic pedigree |url=https://queue.acm.org/detail.cfm?id=3136559 |journal=] |volume=60 |issue=12 |pages=36–45 |doi=10.1145/3132259 |s2cid=6425116 |issn=0001-0782 |access-date=22 November 2023 |archive-date=14 October 2023 |archive-url=https://web.archive.org/web/20231014120907/https://queue.acm.org/detail.cfm?id=3136559 |url-status=live }}</ref> | |||
===2008–2009: Creation=== | |||
The United States is considered more bitcoin-friendly than some other governments.<ref name=capcont>{{cite news|url= http://www.washingtonpost.com/blogs/the-switch/wp/2014/01/27/this-map-shows-which-countries-are-friendly-to-bitcoin/ |title= This map shows which countries are friendly to Bitcoin |publisher= ''The Washington Post'' |work= The Switch |date= 27 January 2014 |accessdate= 28 January 2014 |author= Peterson, Andrea}}</ref> In China, buying bitcoins with ] is subject to restrictions, and bitcoin ] are not allowed to hold bank accounts. | |||
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==Design== | |||
}} | |||
The most important part of the bitcoin system is a public ], called the ''block chain'', that records transactions in bitcoins. A novel solution is that this is accomplished without the intermediation of any single, central authority, since the maintenance of the ledger is performed by a ] of ] running bitcoin software that anyone can join.<ref name="primer" /> Transactions of the form ''payer X sends Y bitcoins to payee Z'' are broadcast to this network using readily available software applications. Network nodes can validate these transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes.<ref name="Antonopoulos2014" /> | |||
{{multiple image | |||
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===The block chain=== | |||
| image1 = Bitcoin old.png | |||
Bitcoin transactions are recorded in a public ledger called the block chain. The block chain is ]; to independently verify the chain of ownership of any and every bitcoin amount, full-featured bitcoin software stores its own copy of it. Approximately six times per hour, a group of accepted transactions, a block, is added to the block chain, which is quickly published to all network nodes. This allows bitcoin software to determine when a particular bitcoin amount has been spent, which is necessary to prevent ] in an environment with no central authority. Whereas a conventional ledger records the transfers of actual ] or ]s that exist apart from it, the block chain is the only place that bitcoins can be said to exist in the form of unspent outputs of transactions.<ref name="Antonopoulos2014" /> | |||
| image2 = Bitcoin.png | |||
| footer = Bitcoin logos made by Satoshi Nakamoto in 2009 (left) and 2010 (right). | |||
===Ownership=== | |||
] | |||
For every transaction output the block chain registers the address to which the output is encumbered. To use the output in a future transaction, the payer must ] the transaction using the corresponding ]. This prevents unauthorized transfers, since only the user knowing the private key can sign the transaction. Network can verify the signature using the ].<ref name="Antonopoulos2014" /> | |||
If the private key is lost, the ] will not recognize any other evidence of ownership;<ref name="primer" /> the coins are then lost and cannot be recovered. For example, in 2013 one user said he lost 7,500 bitcoins, worth $7.5 million at the time, when he discarded a hard drive containing his private key.<ref>{{cite news|title=Man Throws Away 7,500 Bitcoins, Now Worth $7.5 Million|date=29 November 2013|url=http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/|work=CBS DC|accessdate=23 January 2014}}</ref> | |||
===Transactions=== | |||
A transaction must have one or more inputs. For the transaction to be valid, every input must be a digitally signed and previously unspent output of a previous transaction. The use of multiple inputs corresponds to the use of multiple coins in a cash transaction. | |||
A transaction can also have multiple outputs, allowing to make multiple payments in one go. A transaction output can be specified as an arbitrary multiple of satoshi. | |||
Similarly as in a cash transaction, the sum of inputs (coins used to pay) can exceed the intended sum of payments. In such case, an additional output is used, returning the change back to the payer.<ref name="Antonopoulos2014" /> | |||
===Mining=== | |||
] (Mhash/J). Mining hardware common since mid 2014<ref name=AntMiner-S3>{{cite web|title=ANTMINER S3+ -B10|url=https://bitmaintech.com/productDetail.htm?pid=00020140917060843699l3bEXYxL06C0|website=bitmaintech.com|publisher=Bitmain Tech Ltd|accessdate=5 October 2014}}</ref> typically deliver a ten-fold efficiency of 1.3 gigahashes per joule (Ghash/J) or more.<ref name=coinexplorer>{{cite web|title=Bitcoin mining hardware comparison|url=https://coinplorer.com/Hardware|website=coinplorer.com/Hardware|publisher=coinplorer.com|accessdate=5 October 2014}}</ref> And ] mining hardware with 6 Ghash/J has already been announced for 2015.<ref name=Coinbau>{{cite web | last1 = Higgins | first1 = Stan | title = ASIC Maker Seeks to Bring German Efficiency to Bitcoin Mining | url = http://www.coindesk.com/asic-maker-coinbau-german-efficiency-bitcoin-mining/ | date = 20 August 2014 | publisher = CoinDesk | accessdate = 5 October 2014}}</ref>]] | |||
''Mining'' is a record-keeping service.{{refn | group = note | It is misleading to think that there is an analogy between gold mining and bitcoin mining. The fact is that gold miners are rewarded for producing gold, while bitcoin miners are ''not'' rewarded for producing bitcoins; they are rewarded for their record-keeping services.<ref name="Andolfatto2014-03" />}} Miners keep the block chain consistent, complete, and unalterable by repeatedly verifying and collecting newly broadcast transactions into a new group of transactions called a ''block''. | |||
The new block must contain an information that chains it to the previous block and gives the block chain its name. It is a ] - bitcoin uses ] - of the previous block. | |||
Finally, the new block must contain a so-called ''proof-of-work''. The proof-of-work consists of a number called a ''difficulty target'' and a number called a ''nonce'', which is a ] for "a number used only once". Miners have to find such a nonce that gives a hash of the new block smaller than the difficulty target. When the new block is created and distributed to the network, every network node can easily verify the proof.<ref name="Antonopoulos2014" /> | |||
Finding the proof requires significant work, since for a secure cryptographic hash there is only one method to find the requisite nonce: miners try different integer values one at a time, e.g., 1, then 2, then 3, and so on until the requisite output is obtained. The smaller the target number, the longer on average it will take to find a requisite nonce, because the lower the probability that any particular value will produce a hash less than the target. The bitcoin system periodically (every 2016 blocks) adjusts the difficulty target so that the average time the entire network needs to find a nonce is about ten minutes. That way, as computer hardware gets faster over the years, the bitcoin protocol will simply adjust the mining target to make mining always last about ten minutes.<ref name="Antonopoulos2014" /> For example, at the end of April 2014 miners had to try 34,4 quintillion values at average before finding the requisite nonce, while at the end of October 2014 it was 154.6 quintillion values at average. | |||
The proof-of-work together with the fact that the blocks are chained, makes modifications of the block chain extremely hard, because an attacker has to modify not just one block, but also the subsequent blocks, needing to outperform the combined power of the rest of the network, which continues adding new blocks to the original, honest version of the block chain.<ref name="khanbitcoin">{{cite web | last = Ramzan | first = Zulfikar | title = Bitcoin: What is it? | url = http://www.khanacademy.org/economics-finance-domain/core-finance/money-and-banking/bitcoin/v/bitcoin-what-is-it | publisher = The Khan Academy | date = 2014 | accessdate = 5 April 2014}}</ref> | |||
===Supply=== | |||
The successful miner finding the new block is rewarded with newly created bitcoins and transaction fees.<ref name="bloombergvance111413">{{cite web | url = http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race | title = 2014 Outlook: Bitcoin Mining Chips, a High-Tech Arms Race | publisher = Businessweek | date = 14 November 2013 | author = Ashlee Vance | accessdate = 24 November 2013}}</ref> {{as of|2014}}, the reward amounts to 25 newly created bitcoins per block added to the block chain. To claim the reward, a special transaction called a ''coinbase'' is included with the processed payments.<ref name="Antonopoulos2014" /> All bitcoins in circulation can be traced back to such coinbase transactions. The ] specifies that the reward for adding a block will be halved approximately every four years. Eventually, the reward will be removed entirely when an arbitrary limit of 21 million bitcoins is reached ] 2140, and transaction processing will then be rewarded by transaction fees solely.<ref name="KWY">{{cite web | url = http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins/ | title = By reading this article, you're mining bitcoins | publisher = Atlantic Media Co | work = qz.com | date = 17 December 2013 | accessdate = 17 December 2013 | author = Ritchie S. King, Sam Williams, David Yanofsky}}</ref> | |||
Paying a transaction fee is optional, but may speed up confirmation of the transaction.<ref name="txnfee">{{cite web|title=How much will the transaction fee be?|url=https://bitcoin.org/en/faq#how-much-will-the-transaction-fee-be|work=FAQ|publisher=Bitcoin Foundation|accessdate=19 March 2014}}</ref> Payers have an incentive to include such fees because doing so means their transaction will likely be added to the block chain sooner; miners can choose which transactions to process<ref name="EconOfBTC" /> and prefer to include those that pay fees. | |||
===Mining pools=== | |||
{{as of|2013}} mining had become quite competitive, has been compared to an ] and ever more specialized technology is utilized. The most efficient mining hardware makes use of custom designed ]s, which outperform general purpose ]s and use less power as well.<ref>{{cite news|url=http://www.theregister.co.uk/2014/01/17/ten_bitcoin_miners/ |title=Manic miners: Ten Bitcoin generating machines |publisher=The Register | first=Simon | last=Rockman | date=17 January 2014|accessdate=13 February 2014}}</ref> Without access to these purpose built machines, a bitcoin miner is unlikely to earn enough to even cover the cost of the electricity used in his or her efforts.<ref name=purdue/> | |||
The individual ] of winning the reward for adding a block to the block chain decrease with an increasing number of miners. Since the reward for each block can only go to a single bitcoin address, {{as of|2014|lc=y}}, it has become common for miners to join organized ]s,<ref name=boise>{{cite web | url=http://arbiteronline.com/2014/04/03/bitcoins-likely-viable-future/ | title=Bitcoins lose viability | publisher=Boise State Student Media | work=The Arbiter | date=3 April 2014 | accessdate=14 April 2014 | author=Mills, Kelly}}</ref> which split work and reward among all participants and make mining a less risky endeavor. Even for those who join pools, the cost of the electricity necessary to mine may outweigh the rewards from doing so.<ref name=purdue>{{cite web | url=http://www.purdueexponent.org/features/article_46e4aefa-dc11-5c5e-972b-80b4e45a70e1.html | title=Bitcoin offers speedy currency, poses high risks | publisher=The Exponent Online | work=Purdue Exponent | date=9 April 2014 | accessdate=14 April 2014 | author=Bays, Jason}}</ref> | |||
===Wallets=== | |||
{{see also | Digital wallet | Online wallet | Armory (software) | Circle (company)}} | |||
{{Multiple image | |||
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| caption1 = Electrum bitcoin wallet | |||
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| caption2 = Casascius physical bitcoins<ref name="capitalization" /> | |||
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| caption3 = paper wallet with ]s | |||
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| caption4 = Trezor hardware wallet | |||
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The domain name ''bitcoin.org'' was registered on 18 August 2008.<ref>{{Cite news |last=Bernard |first=Zoë |date=2 December 2017 |title=Everything you need to know about Bitcoin, its mysterious origins, and the many alleged identities of its creator |work=Business Insider |url=http://www.businessinsider.com/bitcoin-history-cryptocurrency-satoshi-nakamoto-2017-12 |url-status=live |access-date=15 June 2018 |archive-url=https://web.archive.org/web/20180615010015/http://www.businessinsider.com/bitcoin-history-cryptocurrency-satoshi-nakamoto-2017-12 |archive-date=15 June 2018}}</ref> On 31 October 2008, a link to a ] authored by ] titled ''Bitcoin: A Peer-to-Peer Electronic Cash System'' was posted to a cryptography mailing list.<ref>{{Cite news |last=Finley |first=Klint |date=31 October 2018 |title=After 10 Years, Bitcoin Has Changed Everything—And Nothing |magazine=Wired |url=https://www.wired.com/story/after-10-years-bitcoin-changed-everything-nothing/ |url-status=live |access-date=9 November 2018 |archive-url=https://web.archive.org/web/20181105070656/https://www.wired.com/story/after-10-years-bitcoin-changed-everything-nothing/ |archive-date=5 November 2018}}</ref> Nakamoto implemented the bitcoin software as ] and released it in January 2009.<ref name="NY2011" /> Nakamoto's identity remains unknown.{{r|whoissn}} According to computer scientist ], all individual components of bitcoin originated in earlier academic literature.<ref name=Narayanan2017/> Nakamoto's innovation was their complex interplay resulting in the first decentralized, ], ] tolerant digital cash system, that would eventually be referred to as the first blockchain.<ref name=Narayanan2017/><ref name="te20151031">{{Cite news |last=Economist Staff |date=31 October 2015 |title=Blockchains: The great chain of being sure about things |url=https://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |url-status=live |newspaper=] |archive-url=https://web.archive.org/web/20160703000844/http://www.economist.com/news/briefing/21677228-technology-behind-bitcoin-lets-people-who-do-not-know-or-trust-each-other-build-dependable |archive-date=3 July 2016 |access-date=18 June 2016 }}</ref> Nakamoto's paper was not ]ed and was initially ignored by academics, who argued that it could not work.<ref name=Narayanan2017/> | |||
Bitcoin ] called a ''bitcoin wallet'' allows a user to transact bitcoins. While wallets are often described as a "place to hold"<ref>{{cite web | url = http://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained | title = Bitcoin, Explained | publisher = Mother Jones | work = motherjones.com | date = 10 April 2013 | accessdate = 26 April 2014 | author = Adam Serwer and Dana Liebelson}}</ref> or "store bitcoins",<ref name=3ceos /> due to the nature of the system, bitcoins are inseparable from the block chain transaction ledger. Perhaps a better way to describe a wallet is something that "stores the digital credentials for your bitcoin holdings"<ref name=3ceos>{{cite web | url = http://www.forbes.com/sites/johnvillasenor/2014/04/26/secure-bitcoin-storage-a-qa-with-three-bitcoin-company-ceos/ | title = Secure Bitcoin Storage: A Q&A With Three Bitcoin Company CEOs | publisher = Forbes | work = forbes.com | date = 26 April 2014| accessdate = 26 April 2014 | author = Villasenor, John}}</ref> and "allows you to access (and spend) them". Bitcoin uses ], in which two cryptographic keys, one public and one private, are generated.<ref name="Economist113013Pressure">{{cite news | url = http://www.economist.com/news/technology-quarterly/21590766-virtual-currency-it-mathematically-elegant-increasingly-popular-and-highly | title = Bitcoin: Bitcoin under pressure | work = The Economist | date = 30 November 2013 | accessdate = 30 November 2013}}</ref> A hash of the public key is a bitcoin address, and the private key can be thought of as ownership credentials to that address. At its most basic, a wallet is a collection of these keys. Most bitcoin wallets also include the ability to make transactions, however. | |||
On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the '']''.<ref name="Wired:RFB">{{Cite magazine |last=Wallace, Benjamin |date=23 November 2011 |title=The Rise and Fall of Bitcoin |url=https://www.wired.com/2011/11/mf-bitcoin/ |url-status=live |magazine=Wired |archive-url=https://web.archive.org/web/20131031043919/http://www.wired.com/magazine/2011/11/mf_bitcoin |archive-date=31 October 2013 |access-date=13 October 2012}}</ref> Embedded in this block was the text "The Times 03/Jan/2009 Chancellor on brink of ]", which is the date and headline of an issue of '']'' newspaper.<ref name="NY2011" /> Nine days later, Hal Finney received the first bitcoin transaction: ten bitcoins from Nakamoto.<ref>{{Cite news |last=Popper |first=Nathaniel |date=30 August 2014 |title=Hal Finney, Cryptographer and Bitcoin Pioneer, Dies at 58 |work=] |url=https://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html |url-status=live |access-date=2 September 2014 |archive-url=https://web.archive.org/web/20140903162835/http://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html |archive-date=3 September 2014}}</ref> Wei Dai and Nick Szabo were also early supporters.<ref name="Wired:RFB" /> On May 22, 2010, the first known ] using bitcoin occurred when programmer Laszlo Hanyecz bought two ] pizzas for ₿10,000, in what would later be celebrated as "Bitcoin Pizza Day".<ref>{{cite news |last1=Cooper |first1=Anderson |title=Meet the man who spent millions worth of bitcoin on pizza |url=https://www.cbsnews.com/news/meet-the-man-who-spent-millions-worth-of-bitcoin-on-pizza-60-minutes-2019-05-16 |work=] |date=16 May 2019 |access-date=8 December 2021 |archive-date=8 December 2021 |archive-url=https://web.archive.org/web/20211208180706/https://www.cbsnews.com/news/meet-the-man-who-spent-millions-worth-of-bitcoin-on-pizza-60-minutes-2019-05-16/ |url-status=live }}</ref> | |||
There are several types of implementations. So-called ''full nodes'' validate transactions and blocks they receive, and relay them to connected peers.<ref name="Bitcoin Clients" /> The first wallet program called Bitcoin-Qt was released in 2009 by ] as ] code.<ref name="Bitcoin Clients">{{Cite thesis | url = http://publications.theseus.fi/bitstream/handle/10024/47166/Skudnov_Rostislav.pdf?sequence=1 | first = Rostislav | last = Skudnov | title = Bitcoin Clients | type = Bachelor's Thesis | year = 2012 | publisher = ] | accessdate = 16 January 2014}}</ref> It can be used as a desktop wallet for payments or as a server utility for merchants and other payment services. Bitcoin-Qt, also called ''Satoshi client'', is sometimes referred to as the ] because it serves to define the bitcoin protocol and acts as a standard for other implementations.<ref name="Bitcoin Clients"/> As of version 0.9, Bitcoin-Qt has been renamed Bitcoin Core to more accurately describe its role in the network.<ref>{{cite journal | date = 19 March 2014 | title = Bitcoin Version 0.9.0 Brings Transaction Malleability Fixes, Branding Change | url = http://www.coindesk.com/bitcoin-version-0-9-0-brings-transaction-malleability-fixes-branding-change/ | author = Pete Rizzo | accessdate = 31 October 2014}}</ref> Wallets for mobile devices ubiquitously use ]s to simplify transactions. | |||
===2010–2012: Early growth=== | |||
Perhaps better termed physical wallets, physical bitcoins are ubiquitous in media coverage and combine a novelty coin with a private key printed on paper, metal,<ref name="theverge">{{cite web|last=Staff|first=Verge |url=http://www.theverge.com/2013/12/13/5207256/casascius-maker-of-shiny-physical-bitcoins-shut-down-by-treasury|title=Casascius, maker of shiny physical bitcoins, shut down by Treasury Department |publisher=The Verge |date=13 December 2013|accessdate=10 January 2014}}</ref> wood,<ref name="coindesk">{{cite web | author = Daniel Cawrey (@danielcawrey) | url = http://www.coindesk.com/canadian-man-worlds-first-wood-bitcoin-wallet/ | title = Canadian Man Builds World's First Wooden Bitcoin Wallet | publisher = Coindesk.com | date = 20 December 2013 | accessdate = 10 January 2014}}</ref> or plastic. For those serious about security, storing private keys on paper printouts or in offline ]s is the best option.<ref name=3ceos/> | |||
] estimate that Nakamoto had mined about one million bitcoins<ref>{{Cite news |last=McMillan |first=Robert |title=Who Owns the World's Biggest Bitcoin Wallet? The FBI |magazine=Wired |url=https://www.wired.com/2013/12/fbi-wallet/ |url-status=live |access-date=7 October 2016 |archive-url=https://web.archive.org/web/20161021221609/https://www.wired.com/2013/12/fbi-wallet/ |archive-date=21 October 2016}}</ref> before disappearing in 2010 when he handed the network alert key and control of the ] over to ]. Andresen later became lead developer at the ],<ref>{{cite news |last=Simonite |first=Tom |title=Meet Gavin Andresen, the most powerful person in the world of Bitcoin |date=15 August 2014 |url=https://www.technologyreview.com/2014/08/15/12784/the-man-who-really-built-bitcoin |work=] |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.technologyreview.com/2014/08/15/12784/the-man-who-really-built-bitcoin |url-status=live }}</ref><ref>{{Cite news |last=Odell |first=Matt |date=21 September 2015 |title=A Solution To Bitcoin's Governance Problem |work=TechCrunch |url=https://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |url-status=live |access-date=24 January 2016 |archive-url=https://web.archive.org/web/20160126051521/http://techcrunch.com/2015/09/21/a-solution-to-bitcoins-governance-problem/ |archive-date=26 January 2016}}</ref> an ] founded in September 2012 to promote bitcoin.<ref>{{Cite news |last=Bustillos |first=Maria |date=1 April 2013 |title=The Bitcoin Boom |magazine=The New Yorker |url=https://www.newyorker.com/tech/elements/the-bitcoin-boom |url-status=live |access-date=30 July 2018 |archive-url=https://web.archive.org/web/20180702064450/https://www.newyorker.com/tech/elements/the-bitcoin-boom |archive-date=2 July 2018}}</ref> | |||
After early "]" transactions, the first major users of bitcoin were ]s, such as the ] ]. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9 million, worth about $214 million.<ref name=JEP/>{{rp|222}} | |||
Hardware wallets are the result of the effort to combine paper wallet security with the convenience of online wallets. An example of such a wallet is Trezor (the word "trezor" is a Slavic equivalent for "vault").<ref>{{cite news | title = Meet Trezor, A Bitcoin Safe That Fits Into Your Pocket | url = http://www.forbes.com/sites/ericxlmu/2014/10/15/meet-trezor-a-bitcoin-safe-that-can-fit-into-your-pocket/ | author = Eric Mu | date = 15 October 2014 | accessdate = 31 October 2014}}</ref> | |||
===2013–2014: First regulatory actions=== | |||
===Units=== | |||
In March 2013, the US ] (FinCEN) established regulatory guidelines for "decentralized virtual currencies" such as bitcoin, classifying American bitcoin miners who sell their generated bitcoins as ]es, subject to registration and other legal obligations.<ref>{{cite news |last=Lee |first=Timothy B. |date=19 March 2013 |title=US regulator Bitcoin Exchanges Must Comply With Money Laundering Laws |url=https://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ |url-status=live |archive-url=https://web.archive.org/web/20131021203745/http://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ |archive-date=21 October 2013 |access-date=28 July 2017 |work=]}}</ref> In May 2013, US authorities seized the unregistered ] ].<ref>{{cite news |last=Dillet |first=Romain |title=Feds Seize Assets From Mt. Gox's Dwolla Account, Accuse It Of Violating Money Transfer Regulations |url=https://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/ |work=] |url-status=live |archive-url=https://web.archive.org/web/20131009161856/http://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/ |archive-date=9 October 2013 |access-date=15 May 2013}}</ref> In June 2013, the US ] seized ₿11.02 from a man attempting to use them to buy illegal substances. This marked the first time a government agency had seized bitcoins.<ref>{{Cite news |last=Sampson |first=Tim |year=2013 |title=U.S. government makes its first-ever Bitcoin seizure |work=The Daily Dot |url=http://www.dailydot.com/business/11-bitcoins-seized-government-dea/ |url-status=live |access-date=15 October 2013 |archive-url=https://web.archive.org/web/20130712010826/http://www.dailydot.com/business/11-bitcoins-seized-government-dea/ |archive-date=12 July 2013}}</ref> The FBI seized about ₿30,000 in October 2013 from Silk Road, following the arrest of its founder ].<ref>{{Cite news |last=Hill |first=Kashmir |title=The FBI's Plan For The Millions Worth Of Bitcoins Seized From Silk Road |work=Forbes |url=https://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/ |url-status=live |archive-url=https://web.archive.org/web/20140502154935/http://www.forbes.com/sites/kashmirhill/2013/10/04/fbi-silk-road-bitcoin-seizure/ |archive-date=2 May 2014}}</ref> | |||
The main unit of account of the bitcoin system is bitcoin (BTC,<ref group="note" name="BTCcode" /> XBT,<ref group="note" name="XBTcode" /> or {{nowrap|]}}<ref group="note" name="BTCsym" />).<ref name=btcregs /> | |||
In December 2013, the ] prohibited Chinese financial institutions from using bitcoin.<ref>{{Cite news |last=Kelion, Leo |date=18 December 2013 |title=Bitcoin sinks after China restricts yuan exchanges |work=BBC News |url=https://www.bbc.co.uk/news/technology-25428866 |url-status=live |access-date=20 December 2013 |archive-url=https://web.archive.org/web/20131219214615/http://www.bbc.co.uk/news/technology-25428866 |archive-date=19 December 2013}}</ref> After the announcement, the value of bitcoin dropped,<ref>{{Cite news |date=6 December 2013 |title=China bans banks from bitcoin transactions |work=] |publisher=Reuters |url=https://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html |url-status=live |access-date=31 October 2014 |archive-url=https://web.archive.org/web/20140323102824/http://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html |archive-date=23 March 2014}}</ref> and ] no longer accepted bitcoins for certain services.<ref>{{Cite news |date=7 December 2013 |title=Baidu Stops Accepting Bitcoins After China Ban |work=Bloomberg |location=New York |url=https://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html |url-status=live |access-date=11 December 2013 |archive-url=https://web.archive.org/web/20131210214547/http://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html |archive-date=10 December 2013}}</ref> Buying real-world goods with any virtual currency had been illegal in China since at least 2009.<ref>{{cite web |date=29 June 2009 |title=China bars use of virtual money for trading in real goods |url=http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |url-status=live |archive-url=https://web.archive.org/web/20131129184312/http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |archive-date=29 November 2013 |access-date=10 January 2014 |publisher=English.mofcom.gov.cn}}</ref> | |||
Bitcoin can be broken up into small fragments 0.00000001 BTC, which is one hundred millionth of bitcoin. This unit is called ''satoshi''. Satoshi is the smallest fragment of bitcoin available.<ref name="satoshi unit" /> | |||
===2015–2019=== | |||
There are also two other subunits of bitcoin, and those are called ''millibitcoin'' (mBTC) and ''microbitcoin'' (µBTC). One millibitcoin equals to 0.001 BTC, which is one thousandth of bitcoin, or 100,000 satoshis, or 1,000 µBTC.<ref name="Antonopoulos2014" /> One microbitcoin equals to 0.000001 BTC, which is one millionth of bitcoin, or 100 satoshis, or 0.001 mBTC. | |||
Research produced by the ] estimated that in 2017, there were 2.9 to 5.8 million unique users using a ], most of them using bitcoin.<ref>{{cite web |last1=Hileman |first1=Garrick |last2=Rauchs |first2=Michel |title=Global Cryptocurrency Benchmarking Study |url=https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |url-status=live |archive-url=https://web.archive.org/web/20170410130007/https://www.jbs.cam.ac.uk/fileadmin/user_upload/research/centres/alternative-finance/downloads/2017-global-cryptocurrency-benchmarking-study.pdf |archive-date=10 April 2017 |access-date=14 April 2017 |publisher=Cambridge University}}</ref> In August 2017, the ] software upgrade was activated. Segwit was intended to support the ] as well as improve ].<ref>{{Cite news |last=Vigna |first=Paul |date=21 July 2017 |title=Bitcoin Rallies Sharply After Vote Resolves Bitter Scaling Debate |work=The Wall Street Journal |url=https://www.wsj.com/articles/bitcoin-rallies-sharply-after-vote-resolves-bitter-scaling-debate-1500656084 |access-date=21 November 2023 |archive-date=21 November 2023 |archive-url=https://web.archive.org/web/20231121164350/https://www.wsj.com/articles/bitcoin-rallies-sharply-after-vote-resolves-bitter-scaling-debate-1500656084 |url-status=live }}</ref> SegWit opponents, who supported larger blocks as a scalability solution, ] to create ], one of many ].<ref>{{Cite news |last=Selena Larson |date=1 August 2017 |title=Bitcoin split in two, here's what that means |work=CNN Tech |publisher=Cable News Network |url=https://money.cnn.com/2017/08/01/technology/business/bitcoin-cash-new-currency/index.html |url-status=live |access-date=2 April 2018 |archive-url=https://web.archive.org/web/20180227214042/https://money.cnn.com/2017/08/01/technology/business/bitcoin-cash-new-currency/index.html |archive-date=27 February 2018}}</ref> | |||
In December 2017, the first ] on bitcoin was introduced by the ] (CME).<ref>{{Cite web |url=https://www.cnbc.com/2017/12/17/worlds-largest-futures-exchange-set-to-launch-bitcoin-futures-sunday-night.html |title=Bitcoin debuts on the world's largest futures exchange, and prices fall slightly |date=17 December 2017 |access-date=19 January 2024 |website=CNBC |last=Cheng |first=Evelyn |archive-date=18 January 2024 |archive-url=https://web.archive.org/web/20240118182719/https://www.cnbc.com/2017/12/17/worlds-largest-futures-exchange-set-to-launch-bitcoin-futures-sunday-night.html |url-status=live }}</ref> | |||
In a press release issued 7 October 2014, the Bitcoin Foundation revealed a formal plan to apply for an ] currency code for bitcoin.<ref name = "standardize" /> The press release mentions BTC and XBT as the leading candidates.<ref>{{cite web | title = Press Release October 7, 2014: Bitcoin Foundation Financial Standards Working Group Leads the Way for Mainstream Bitcoin Adoption | url = https://bitcoinfoundation.org/press-releases/press-release-october-7-2014-bitcoin-foundation-financial-standards-working-group-leads-the-way-for-mainstream-bitcoin-adoption-2/ | publisher = ] | work = Press Release | date = 7 October 2014 | accessdate = 7 November 2014}}</ref> | |||
In February 2018, the price crashed after China imposed a complete ban on bitcoin trading.<ref>{{Cite news |last=French |first=Sally |date=9 February 2017 |title=Here's proof that this bitcoin crash is far from the worst the cryptocurrency has seen |publisher=Market Watch |url=https://www.marketwatch.com/story/heres-proof-that-this-bitcoin-crash-is-far-from-the-worst-the-cryptocurrency-has-seen-2018-02-09 |url-status=live |access-date=3 July 2018 |archive-url=https://web.archive.org/web/20180703220246/https://www.marketwatch.com/story/heres-proof-that-this-bitcoin-crash-is-far-from-the-worst-the-cryptocurrency-has-seen-2018-02-09 |archive-date=3 July 2018}}</ref> The percentage of bitcoin trading in the Chinese ] fell from over 90% in September 2017 to less than 1% in June 2018.<ref>{{Cite news |date=7 July 2018 |title=RMB Bitcoin trading falls below 1 pct of world total |publisher=Xinhuanet |agency=] |url=http://www.xinhuanet.com/english/2018-07/07/c_137308879.htm |url-status=live |access-date=10 July 2018 |archive-url=https://web.archive.org/web/20180710225218/http://www.xinhuanet.com/english/2018-07/07/c_137308879.htm |archive-date=10 July 2018}}</ref> During the same year, bitcoin prices were negatively affected by several hacks or thefts from cryptocurrency exchanges.<ref>{{Cite news |last=Chavez-Dreyfuss |first=Gertrude |date=3 July 2018 |title=Cryptocurrency exchange theft surges in first half of 2018: report |work=Reuters |url=https://www.reuters.com/article/us-crypto-currencies-ciphertrace/cryptocurrency-exchange-theft-surges-in-first-half-of-2018-report-idUSKBN1JT1Q5 |url-status=live |access-date=10 July 2018 |archive-url=https://web.archive.org/web/20180704120854/https://www.reuters.com/article/us-crypto-currencies-ciphertrace/cryptocurrency-exchange-theft-surges-in-first-half-of-2018-report-idUSKBN1JT1Q5 |archive-date=4 July 2018}}</ref> | |||
===Privacy=== | |||
In traditional banking system, privacy of users is guaranteed by ], and it is achieved by limiting access to information to the parties involved and to the trusted third party. | |||
===2020–present=== | |||
In the bitcoin system privacy is achieved by not identifying owners of bitcoin addresses while making other transaction data public. While bitcoin users are not identified by name, transactions can be linked to individuals and companies,<ref>{{cite web | url=http://www.technologyreview.com/news/518816/mapping-the-bitcoin-economy-could-reveal-users-identities/ | title=Mapping the Bitcoin Economy Could Reveal Users’ Identities | work=MIT Technology Review | date=5 September 2013 | accessdate=2 April 2014 | author=Simonite, Tom}}</ref> since transactions are viewable by everyone. Additionally, exchanges where people buy and sell bitcoins for cash, may be required to collect personal information.<ref name="5facts">{{cite news | url=http://www.washingtonpost.com/blogs/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2/ | title=Five surprising facts about Bitcoin | publisher=The Washington Post | work=washingtonpost.com | date=21 August 2013 | accessdate=2 April 2014 | author=Lee, Timothy}}</ref> To maintain financial privacy, a different bitcoin address for each transaction should be used,<ref>{{cite web | url=http://www.wired.co.uk/news/archive/2013-06/06/bitcoin-retail | title=How Bitcoin lets you spy on careless companies | publisher=Conde Nast | work=wired.co.uk | date=6 June 2013 | accessdate=2 April 2014 | author=McMillan, Robert}}</ref> but multi-input transactions reveal that all their inputs belong to the same owner. That is why users concerned about privacy rely on so-called mixing services that allow users to trade the coins they own for coins with different transaction histories.<ref>{{cite news | url=http://www.forbes.com/sites/jonmatonis/2013/06/05/the-politics-of-bitcoin-mixing-services/ | title=The Politics Of Bitcoin Mixing Services | publisher=Forbes | work=forbes.com | date=5 June 2013 | accessdate=2 April 2014 | author=Matonis, Jon}}</ref> | |||
] |date=4 December 2024 |url=https://fred.stlouisfed.org/graph/?g=1BVJt |access-date=4 December 2024 |publisher=]}}</ref>}} December 1, 2014 - <br> December 4, 2024]] | |||
In 2020, some major companies and institutions started to acquire bitcoin: ] invested $250 million in bitcoin as a ],<ref>{{Cite news |date=13 September 2021 |title=MicroStrategy buys another $250m worth of bitcoin in hope of 100X price growth |url=https://www.independent.co.uk/tech/microstrategy-bitcoin-crypto-price-prediction-b1919178.html |access-date=22 November 2023 |work=] |first=Anthony |last=Cuthbertson |language=en |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.independent.co.uk/tech/microstrategy-bitcoin-crypto-price-prediction-b1919178.html |url-status=live }}</ref> ], $50 million,<ref>{{cite news |author=Oliver Effron |title=Square just bought $50 million in bitcoin |url=https://www.cnn.com/2020/10/08/business/square-bitcoin-crypto-investment/index.html |access-date=22 October 2020 |work=CNN |archive-date=24 October 2020 |archive-url=https://web.archive.org/web/20201024101610/https://www.cnn.com/2020/10/08/business/square-bitcoin-crypto-investment/index.html |url-status=live }}</ref> and ], $100 million.<ref>{{cite news |url=https://www.bloomberg.com/news/articles/2020-12-10/169-year-old-insurer-massmutual-invests-100-million-in-bitcoin |title=169-Year-Old MassMutual Invests $100 Million in Bitcoin |date=11 December 2020 |work=Bloomberg |access-date=26 December 2020 |author=Olga Kharif |archive-date=19 December 2020 |archive-url=https://web.archive.org/web/20201219220543/https://www.bloomberg.com/news/articles/2020-12-10/169-year-old-insurer-massmutual-invests-100-million-in-bitcoin |url-status=live }}</ref> In November 2020, ] added support for bitcoin in the US.<ref>{{cite news |date=13 November 2020 |title=PayPal says all users in US can now buy, hold and sell cryptocurrencies |url=https://techcrunch.com/2020/11/12/paypal-says-all-users-in-u-s-can-now-buy-hold-and-sell-cryptocurrencies/ |access-date=26 November 2020 |work=Techcrunch |archive-date=24 November 2020 |archive-url=https://web.archive.org/web/20201124050031/https://techcrunch.com/2020/11/12/paypal-says-all-users-in-u-s-can-now-buy-hold-and-sell-cryptocurrencies/ |url-status=live }}</ref> | |||
In February 2021, bitcoin's ] reached $1 trillion for the first time.<ref>{{Cite news |last1=Chavez-Dreyfuss |first1=Gertrude |last2=Wilson |first2=Tom |date=19 February 2021 |title=Bitcoin hits $1 trillion market cap, surges to fresh all-time peak |language=en-US |work=Reuters |url=https://www.reuters.com.article/idUSKBN2AJ0GC/ |access-date=24 November 2023}}</ref> In November 2021, the ] ] upgrade was activated, adding support for ]s, improved functionality of ]s and ].<ref>{{cite news |last=Sigalos |first=MacKenzie |date=14 November 2021 |title=Bitcoin's biggest upgrade in four years just happened – here's what changes |url=https://www.cnbc.com/2021/11/14/bitcoin-taproot-upgrade-what-it-means-for-investors.html |access-date=15 November 2021 |work=CNBC |archive-date=14 November 2021 |archive-url=https://web.archive.org/web/20211114215032/https://www.cnbc.com/2021/11/14/bitcoin-taproot-upgrade-what-it-means-for-investors.html |url-status=live }}</ref> Before, bitcoin only used a custom ] with the ] algorithm to produce ].<ref>{{Cite book |last1=Van Hijfte |first1=Stijn |title=Blockchain Platforms: A Look at the Underbelly of Distributed Platforms |publisher=Morgan & Claypool Publishers |year=2020 |isbn=978-1681738925}}</ref>{{rp|101}} In September 2021, bitcoin became ] in ], alongside the US dollar.<ref name=BTCSVSept7FT/> In October 2021, the first bitcoin futures ] (ETF), called BITO, from ] was approved by the ] and listed on the ].<ref>{{Cite web |url=https://www.wsj.com/articles/a-bitcoin-etf-is-almost-here-what-does-that-mean-for-investors-11634376601 |title=A Bitcoin ETF Is Here. What Does That Mean for Investors? |date=19 October 2021 |access-date=11 January 2024 |website=The Wall Street Journal |last=Wursthorn |first=Michael |url-access=subscription |archive-date=10 January 2024 |archive-url=https://web.archive.org/web/20240110200308/https://www.wsj.com/articles/a-bitcoin-etf-is-almost-here-what-does-that-mean-for-investors-11634376601 |url-status=live }}</ref> | |||
Comparing privacy levels, it has been suggested that bitcoin payments should not be considered more private than credit card payments.<ref>{{cite web | url = http://www.hbarel.com/bitcoin-does-not-provide-anonymity | publisher = hbarel.com | title = Bitcoin does not provide anonymity | date = 3 April 2014 | author = Bar-El, Hagai | accessdate = 31 October 2014}}</ref> | |||
In May and June 2022, the bitcoin price fell following the collapses of ], a ],<ref>{{cite news|last=Browne|first=Ryan|date=10 May 2022|title=Bitcoin investors are panicking as a controversial crypto experiment unravels|url=https://www.cnbc.com/2022/05/10/bitcoin-btc-investors-panic-as-terrausd-ust-sinks-below-1-peg.html|work=CNBC|access-date=11 May 2022|archive-date=11 May 2022|archive-url=https://web.archive.org/web/20220511021259/https://www.cnbc.com/2022/05/10/bitcoin-btc-investors-panic-as-terrausd-ust-sinks-below-1-peg.html|url-status=live}}</ref> and the ], a cryptocurrency loan company.<ref>{{cite news|last1=Milmo|first1=Dan|title=Bitcoin value slumps below $20,000 in cryptocurrencies turmoil|url=https://www.theguardian.com/technology/2022/jun/18/bitcoin-value-falls-cryptocurrency-markets-turmoil|access-date=19 June 2022|work=The Guardian|date=18 June 2022|language=en|archive-date=18 June 2022|archive-url=https://web.archive.org/web/20220618231120/https://www.theguardian.com/technology/2022/jun/18/bitcoin-value-falls-cryptocurrency-markets-turmoil|url-status=live}}</ref><ref>{{cite news|last=Yaffe-Bellany|first=David|date=13 June 2022|title=Celsius Network Leads Crypto Markets Into Another Free Fall|url=https://www.nytimes.com/2022/06/13/technology/bitcoin-ether-price.html|work=The New York Times|access-date=14 June 2022|archive-date=14 June 2022|archive-url=https://web.archive.org/web/20220614030021/https://www.nytimes.com/2022/06/13/technology/bitcoin-ether-price.html|url-status=live}}</ref> | |||
===Fungibility=== | |||
] of fiat money is established by the ] law. In case of bitcoin no law establishes it is fungible. Wallets and similar software technically handle bitcoins as equivalent, establishing the basic level of fungibility to bitcoin. Researchers point out, however, that the history of every single bitcoin is registered and publicly available in the block chain ledger, and that some users may refuse to accept bitcoins coming from controversial transactions, which would harm their fungibility.<ref>{{cite conference | first1 = Eli | last1 = Ben-Sasson | first2 = Alessandro | last2 = Chiesa | first3 = Christina | last3 = Garman | first4 = Matthew | last4 = Green | first5 = Ian | last5 = Miers | first6 = Eran | last6 = Tromer | first7 = Madars | last7 = Virza | booktitle = 2014 IEEE Symposium on Security and Privacy | title = Zerocash: Decentralized Anonymous Payments from Bitcoin | url = http://zerocash-project.org/media/pdf/zerocash-oakland2014.pdf | date = 2014 | accessdate = 31 October 2014}}</ref> | |||
In 2023, ordinals—]s (NFTs)—on bitcoin, went live.<ref>{{Cite journal |last=Behrendt |first=Philipp |date=2023 |title=Taxation of the New Age: New Guidance for the World of Digital Assets |url=https://heinonline.org/HOL/Page?handle=hein.journals/jtaxpp25&id=105&div=&collection= |journal=Journal of Tax Practice & Procedure |volume=25 |pages=47 |access-date=21 November 2023 |archive-date=21 November 2023 |archive-url=https://web.archive.org/web/20231121164911/https://heinonline.org/HOL/Page?handle=hein.journals/jtaxpp25&id=105&div=&collection= |url-status=live }}</ref> As of June 2023, River Financial estimated that bitcoin had 81.7 million users, about 1% of the global population.<ref>{{cite web |date=2024-03-01 |title=As banks buy up bitcoins, who else are the 'Bitcoin whales'? |url=https://www.bbc.com/news/technology-68434579 |access-date=2024-03-14 |website=BBC Home}}</ref> In January 2024, the first 11 US ] bitcoin ]s began trading, offering direct exposure to bitcoin for the first time on American stock exchanges.<ref>{{Cite news |last=Schmitt |first=Will |date=12 January 2024 |title=Bitcoin trading volumes surge after debut of long-awaited US ETFs |url=https://www.ft.com/content/f30ece62-0f1c-492a-8ccd-63ec9730573c |access-date=12 January 2024 |work=Financial Times |archive-date=12 January 2024 |archive-url=https://web.archive.org/web/20240112025105/https://www.ft.com/content/f30ece62-0f1c-492a-8ccd-63ec9730573c |url-status=live }}</ref><ref>{{cite news|last1=Lang|first1=Hannah|title=US bitcoin ETFs see $4.6B in volume in first day of trading|url=https://www.reuters.com/technology/spot-bitcoin-etfs-start-trading-big-boost-crypto-industry-2024-01-11/|access-date=12 January 2024|work=Reuters|date=11 January 2024|language=en}}</ref> In December 2024, bitcoin price reached $100,000 for the first time, as ] ] promised to make the US the "crypto capital of the planet" and to stockpile bitcoin.<ref>{{cite news|url=https://www.reuters.com/technology/bitcoin-tops-100000-optimism-over-trump-crypto-plans-2024-12-05/|title=Bitcoin storms above $100,000 as Trump 2.0 fuels crypto euphoria|work=Reuters|date=2024-12-05}}</ref> The same month, ], the world's largest ], recommended investors to allocate up to 2% of their ] to bitcoin.<ref>{{cite news|url=https://www.reuters.com/markets/us/blackrock-recommends-bitcoin-portfolio-weighting-up-2-interested-investors-2024-12-12/ | title=BlackRock recommends bitcoin portfolio weighting of up to 2% for interested investors|date=2024-12-12|first=Suzanne|last= McGee|work=Reuters}}</ref> | |||
==History== | |||
{{main|History of Bitcoin|l1=History of bitcoin}} | |||
Bitcoin was first mentioned in a research paper published on 31 October 2008 under the name Satoshi Nakamoto<ref group="note" name="Satoshi" /> and released in January 2009.<ref name="paper" /> | |||
==Design== | |||
One of the first supporters, adopters, contributor to bitcoin and receiver of the first bitcoin transaction was a cryptographer, ], futurist and programmer ]. Finney "downloaded the bitcoin software the day it was released", and Nakamoto sent Finney 10 bitcoins the day after that.<ref>{{cite news|last1=Popper|first1=Nathaniel|title=Hal Finney, Cryptographer and Bitcoin Pioneer, Dies at 58|url=http://www.nytimes.com/2014/08/31/business/hal-finney-cryptographer-and-bitcoin-pioneer-dies-at-58.html?_r=1|accessdate=2 September 2014|work=NYTimes|date=30 August 2014}}</ref> | |||
{{Main|Bitcoin protocol}} | |||
===Units and divisibility=== | |||
Other early supporters were Wei Dai, creator of bitcoin predecessor b-money, and Nick Szabo, creator of bitcoin predecessor bit gold.<ref name="WallaceWired11">{{cite news | url = http://www.wired.com/magazine/2011/11/mf_bitcoin/ | title = The Rise and Fall of Bitcoin | work = Wired | date = 23 November 2011 | accessdate = 4 November 2013 | author = Wallace, Benjamin}}</ref> | |||
The ] of the bitcoin system is the ''bitcoin''. It is most commonly represented with the ] ₿<ref name="unicode-10" /> and the ] BTC. However, the BTC code does not conform to ] as BT is the country code of Bhutan,<ref name="ssrn.3383734">{{Cite journal |last1=Alexander |first1=Carol |last2=Imeraj |first2=Arben |date=2019 |title=Introducing the BITIX: The Bitcoin Fear Gauge |url=https://www.ssrn.com/abstract=3383734 |journal=] |language=en |doi=10.2139/ssrn.3383734 |issn=1556-5068|quote=XBT satisfies the norm ‘ISO 4217’ by the International Organisation for Standardisation (ISO) as BTC goes against the name of Bhutan’s currency. In general, transaction instruments that are not national currencies, like gold or silver, begin with an X. However, the symbol XBT is not officially recognised by ISO.}}</ref> and ISO 4217 requires the first letter used in global commodities to be 'X'.<ref name="ssrn.3383734"/> XBT, a code that conforms to ] though not officially part of it,<ref name="ssrn.3383734"/> is used by ]<ref>{{Cite news |last=Romain Dillet |date=9 August 2013 |title=Bitcoin Ticker Available On Bloomberg Terminal For Employees |work=] |url=https://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |url-status=live |access-date=2 November 2014 |archive-url=https://web.archive.org/web/20141101232825/http://techcrunch.com/2013/08/09/bitcoin-ticker-available-on-bloomberg-terminal/ |archive-date=1 November 2014}}</ref> | |||
No uniform ] convention exists; some sources use ''Bitcoin'', capitalized, to refer to the technology and ], and ''bitcoin'', lowercase, for the unit of account.<ref>{{Cite magazine |last=Bustillos, Maria |date=2 April 2013 |title=The Bitcoin Boom |url=https://www.newyorker.com/tech/elements/the-bitcoin-boom |url-status=live |magazine=] |archive-url=https://web.archive.org/web/20140727185121/http://www.newyorker.com/tech/elements/the-bitcoin-boom |archive-date=27 July 2014 |access-date=22 December 2013}}</ref> The '']'' and the '']'' use the capitalized and lowercase variants without distinction.<ref>, '']''</ref><ref> {{Webarchive|url=https://web.archive.org/web/20220503092252/http://dictionary.cambridge.org/dictionary/english/bitcoin |date=3 May 2022 }}, '']''</ref> | |||
In 2009, an ] in an early bitcoin client was found that allowed large numbers of bitcoins to be created.<ref name="bug events" /> | |||
One bitcoin is divisible to eight decimal places.<ref name="Antonopoulos2014" />{{rp|ch. 5}} Units for smaller amounts of bitcoin are the millibitcoin (mBTC), equal to {{frac|1|1000}} bitcoin, and the satoshi{{efn|name=satoshi|Named after ]}} (sat), representing {{frac|1|{{val|100000000}}}} (one hundred millionth) bitcoin, the smallest amount possible.<ref name="satoshi unit" /> 100,000 satoshis are one mBTC.<ref>{{Cite news |last1=Katie Pisa |last2=Natasha Maguder |date=9 July 2014 |title=Bitcoin your way to a double espresso |work=CNN |url=http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |url-status=live |access-date=23 April 2015 |archive-url=https://web.archive.org/web/20150618072429/http://edition.cnn.com/2014/06/18/business/bitcoin-your-way-to-a-double-espresso/ |archive-date=18 June 2015 }}</ref> | |||
In March 2013, a technical glitch caused a fork in the block chain, with one half of the network adding blocks to one version of the chain and the other half adding to another. For six hours two bitcoin networks operated at the same time, each with its own version of the transaction history. The core developers called for a temporary halt to transactions, sparking a sharp sell-off. Normal operation was restored when the majority of the network downgraded to version 0.7 of the bitcoin software.<ref name="bug events">{{cite web|last=Buterin |first=Vitalik |url=http://bitcoinmagazine.com/3668/bitcoin-network-shaken-by-blockchain-fork/ |title=Bitcoin Network Shaken by Blockchain Fork |publisher=Bitcoin Magazine |date=12 March 2013|accessdate=17 January 2014}}</ref> | |||
===Blockchain=== | |||
Some mainstream websites began accepting bitcoins ] 2013. ] started in November 2012<ref>{{cite web |url=http://en.blog.wordpress.com/2012/11/15/pay-another-way-bitcoin/ |title=Pay Another Way: Bitcoin |last=Skelton |first=Andy |date=15 November 2012 |publisher=] |accessdate=24 April 2014}}</ref> followed by ] in April 2013,<ref>{{cite web |url=http://mashable.com/2013/04/17/okcupid-bitcoin/|title=OKCupid Now Accepts Bitcoin|last=Franceschi-Bicchierai|first=Lorenzo|date=18 April 2013 |publisher=] |accessdate=24 April 2014}}</ref> ] in November 2013,<ref name="powersellersunite.com">{{cite web | url = http://www.powersellersunite.com/about45219.html | title = Atomic Mall adds Bitcoin payments for approved merchants | author = AtomicMall.com | work = powersellersunite.com | date = 17 November 2013 | accessdate = 8 April 2014}}</ref> ]<ref name=tigger/> and ] in January 2014,<ref name=overstock/> ] in June 2014,<ref>{{cite web |url=http://techcrunch.com/2014/06/11/expedia-now-accepts-bitcoin-for-your-crypto-vacations/ |title=Expedia Now Accepts Bitcoin For Your Crypto-Vacations |last=Biggs |first=John |date=11 June 2014 |publisher=] |accessdate=12 June 2014}}</ref> and ] and ] in July 2014.<ref>{{cite web |first=Mike |last=Flacy |title=Dell, Newegg Start Accepting Bitcoin as Payment |publisher=Digital Trends |date=19 July 2014 |url=http://www.digitaltrends.com/web/dell-newegg-start-accepting-bitcoin-payment/#!bv9oFm |accessdate=5 August 2014}}</ref>{{refn | group = note | name = processors | Some of these firms use bitcoin payment processors such as ] and ] and do not handle or store bitcoins themselves.<ref>{{cite news | first1 = Gertrude | last1 = Chavez-Dreyfuss | first2 = Michael | last2 = Connor | title = Bitcoin shows staying power as online merchants chase digital sparkle | date = 28 August 2014 | publisher = Reuters | url = http://www.reuters.com/article/2014/08/28/us-usa-bitcoin-retailers-analysis-idUSKBN0GS0AG20140828| accessdate = 28 August 2014}}</ref>}} Certain ] or ] groups such as the ] accept bitcoin donations.<ref name="EFF2013">{{cite web | url=https://www.eff.org/deeplinks/2013/05/eff-will-accept-bitcoins-support-digital-liberty | title=EFF Will Accept Bitcoins to Support Digital Liberty | publisher=Electronic Frontier Foundation | date=17 May 2013 | accessdate=27 April 2014 | author=Cindy Cohn, Peter Eckersley, Rainey Reitman, and Seth Schoen}}</ref> (Although this organization stopped accepting bitcoins in 2011<ref>{{cite web | url=https://www.eff.org/deeplinks/2011/06/eff-and-bitcoin | title=EFF and Bitcoin | publisher=Electronic Frontier Foundation | date=20 June 2011 | accessdate=16 April 2014 | author=Cohn, Cindy}}</ref> and began again in 2013.<ref name="EFF2013" />) | |||
{{further|Blockchain#Structure and design}} | |||
As a ] system, bitcoin operates without a central authority or single administrator,<ref name=Gervais2014>{{Cite journal |last1=Gervais |first1=Arthur |last2=Karame |first2=Ghassan O. |last3=Capkun |first3=Vedran |last4=Capkun |first4=Srdjan |date=May 2014 |title=Is Bitcoin a Decentralized Currency? |url=https://ieeexplore.ieee.org/document/6824541 |journal=] |volume=12 |issue=3 |pages=54–60 |doi=10.1109/MSP.2014.49 |s2cid=13948781 |issn=1540-7993 |access-date=22 November 2023 |archive-date=19 November 2023 |archive-url=https://web.archive.org/web/20231119101600/https://ieeexplore.ieee.org/document/6824541/ |url-status=live }}</ref> so that anyone can create a new bitcoin address and transact without needing any approval.{{r|Antonopoulos2014|page=ch. 1}} This is accomplished through a specialized ] called a '']'' that records bitcoin transactions.{{r|econbc}} | |||
The blockchain is implemented as an ordered list of ''blocks''. Each block contains a ] ] of the previous block,<ref name="econbc" /> chaining them in chronological order.<ref name="Antonopoulos2014" />{{rp|ch. 7}}<ref name="econbc" /> The blockchain is maintained by a ] network.<ref name=JEP/>{{rp|215–219}} Individual blocks, public addresses, and transactions within blocks are public information, and can be examined using a blockchain explorer.<ref>{{Cite web| url=https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8301.pdf| publisher=National Institute of Standards Technology (NIST)| access-date=29 December 2022| title=Blockchain Networks: Token Design and Management Overview| page=32| archive-date=24 December 2022| archive-url=https://web.archive.org/web/20221224003108/https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8301.pdf| url-status=live}}</ref> | |||
The first law enforcement events occurred in May 2013, when assets belonging to the ] exchange were seized by Department of Homeland Security.<ref>{{cite news |last=Dillet |first=Romain |title=Feds Seize Assets From Mt. Gox's Dwolla Account, Accuse It Of Violating Money Transfer Regulations |url= http://techcrunch.com/2013/05/16/mt-gox-dwolla-account-money-seizure/ |work=TechCrunch |date=16 May 2013 |accessdate=15 May 2013}}</ref> The ] drug market website was shut down by the FBI in October 2013.<ref>{{cite news |url= http://www.bloomberg.com/news/2013-10-03/fbi-snags-silk-road-boss-with-own-methods.html|title=FBI Snags Silk Road Boss With Own Methods|work=Bloomberg|location=New York|date=3 October 2013|accessdate=27 October 2013|author=Farrell, Greg}}</ref> | |||
Nodes validate and broadcast transactions, each maintaining a copy of the blockchain for ownership verification.<ref>{{Cite news |last=Sparkes, Matthew |date=9 June 2014 |title=The coming digital anarchy |work=The Daily Telegraph |url=https://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |url-status=live |access-date=7 January 2015 |archive-url=https://web.archive.org/web/20150123190900/http://www.telegraph.co.uk/technology/news/10881213/The-coming-digital-anarchy.html |archive-date=23 January 2015}}</ref> A new block is created every 10 minutes on average, updating the blockchain across all nodes without central oversight. This process tracks bitcoin spending, ensuring each bitcoin is ]. Unlike a traditional ledger that tracks physical currency, bitcoins exist digitally as ].<ref name="Antonopoulos2014" />{{rp|ch. 5}} | |||
In October 2013, Chinese internet giant ] had allowed clients of website security services to pay with bitcoins.<ref>{{cite web | url=http://www.businessinsider.com/chinas-google-is-now-accepting-bitcoin-2013-10 | title=China's Google Is Now Accepting Bitcoin | publisher=Business Insider, Inc | work=businessinsider.com | date=15 October 2013 | accessdate=26 December 2013 | author=Kapur, Saranya}}</ref> During November 2013, the ]-based bitcoin exchange ] overtook the Japan-based Mt. Gox and the Europe-based ] to become the largest bitcoin trading exchange by trade volume.<ref>{{cite web|url=http://techcrunch.com/2013/11/18/btc-china-series-a/ |title=As Chinese Investors Pile Into Bitcoin, China's Oldest Exchange, BTC China, Raises $5M From Lightspeed |publisher=TechCrunch|date=18 November 2013|author=Natasha Lomas|accessdate=10 January 2014}}</ref> On 19 November 2013, the value of a bitcoin on the Mt. Gox exchange soared to a peak of US$900 after a United States Senate committee hearing was told by the FBI that virtual currencies are a legitimate financial service.<ref>{{cite news|url=http://www.bbc.co.uk/news/technology-24986264 |title=BBC News - 'Legitimate' Bitcoin's value soars after Senate hearing |publisher=Bbc.co.uk|date=19 November 2013|accessdate=10 January 2014}}</ref> On the same day, one bitcoin traded for over ]¥6780 (US$1,100) in China.<ref>{{cite news|url=http://www.zdnet.com/cn/china-no-plans-yet-to-legalize-use-of-bitcoins-7000023512/|title=China no plans yet to legalize use of Bitcoins|work=ZDNet|date=22 November 2013|accessdate=27 November 2013|last=Lee|first=Cyrus}}</ref> On 5 December 2013, the ] prohibited Chinese financial institutions from using bitcoins.<ref name="ccontrols">{{cite news | url = http://www.bbc.co.uk/news/technology-25428866 | title = Bitcoin sinks after China restricts yuan exchanges | publisher = BBC | work = bbc.com | date = 18 December 2013 | accessdate = 20 December 2013 | author = Kelion, Leo}}</ref> After the announcement, the value of bitcoins dropped<ref>{{cite news | date = 6 December 2013 | url = http://www.smh.com.au/business/markets/currencies/china-bans-banks-from-bitcoin-transactions-20131206-2yugy.html | title = China bans banks from bitcoin transactions | work = ] | publisher = Reuters | accessdate = 31 October 2014}}</ref> and Baidu no longer accepted bitcoins for certain services.<ref name="bloomberg">{{cite news |url=http://www.bloomberg.com/news/2013-12-07/baidu-stops-accepting-bitcoins-after-china-ban.html|title=Baidu Stops Accepting Bitcoins After China Ban |work=Bloomberg |location=New York|date=7 December 2013|accessdate=11 December 2013}}</ref> Buying real-world goods with any virtual currency had been illegal in China since at least 2009.<ref>{{cite web|url=http://english.mofcom.gov.cn/aarticle/newsrelease/commonnews/200906/20090606364208.html |title=China bars use of virtual money for trading in real goods |publisher=English.mofcom.gov.cn |date=29 June 2009|accessdate=10 January 2014}}</ref> | |||
===Addresses and transactions=== | |||
The first bitcoin ATM was installed in October 2013 in ], British Columbia, Canada.<ref>{{cite news | url = http://www.wired.com/wiredenterprise/2013/10/bitcoin_atm_gallery/ | title = Take a tour of Robocoin, the world’s first Bitcoin ATM | first = Robert | last = McMillan | date = 29 October 2013 | work = Wired | accessdate = 31 October 2014}}</ref> | |||
] | |||
In the blockchain, bitcoins are linked to specific addresses that are hashes of a ]. Creating an address involves generating a random ] and then computing the corresponding address. This process is almost instant, but the reverse (finding the private key for a given address) is nearly impossible.<ref name="Antonopoulos2014" />{{rp|ch. 4}} Publishing a bitcoin address does not risk its private key, and it is extremely unlikely to accidentally generate a used key with funds. To use bitcoins, owners need their private key to ] transactions, which are verified by the network using the public key, keeping the private key secret.<ref name="Antonopoulos2014" />{{rp|ch. 5}} | |||
Bitcoin transactions use a ]-like ],{{r|Antonopoulos2014|p=ch. 5}} involving one or more inputs and outputs. When sending bitcoins, a user specifies the recipients' addresses and the amount for each output. This allows sending bitcoins to several recipients in a single transaction. To prevent double-spending, each input must refer to a previous unspent output in the blockchain.<ref name="EconOfBTC">{{Cite conference |last1=Kroll |first1=Joshua A. |last2=Davey |first2=Ian C. |last3=Felten |first3=E. |title=The Economics of Bitcoin Mining, or Bitcoin in the Presence of Adversaries |conference=The Twelfth Workshop on the Economics of Information Security (WEIS 2013) |location=Washington, DC|date= 11–12 June 2013|s2cid=2794725 }}</ref> Using multiple inputs is similar to using multiple coins in a cash transaction. As in a cash transaction, the sum of inputs can exceed the intended sum of payments. In such a case, an additional output can return the change back to the payer.<ref name="EconOfBTC" /> Unallocated input satoshis in the transaction become the transaction fee.<ref name="EconOfBTC" /> | |||
With roughly 12 million existing bitcoins in November 2013,<ref name="raskin">{{cite news |url= http://www.bloomberg.com/news/2013-11-18/u-s-agencies-to-say-bitcoins-offer-legitimate-benefits.html |title= U.S. Agencies to Say Bitcoins Offer Legitimate Benefits |date= 18 November 2013 |accessdate= 24 November 2013 |first= Max |last= Raskin |work= Bloomberg}}</ref> the new price increased the ] for bitcoin to at least US$7.2 billion.<ref>{{cite web|author=Todd Wasserman|url=http://mashable.com/2013/11/18/bitcoin-600/ |title=Bitcoin Tops $600, Up 60x Over the Last Year |publisher=Mashable.com |date=18 November 2013|accessdate=10 January 2014}}</ref> By 23 November 2013, the total market capitalization of bitcoin exceeded US$10 billion for the first time.<ref>{{cite web | url = http://blog.panampost.com/joel-fensch/2014/01/02/bitcoin-set-to-boom-in-latin-america/ | title = Bitcoin Set to Boom in Latin America | author = Joel Fensch | publisher = Blog.panampost.com | date = 2 January 2014 | accessdate = 7 January 2014}}</ref> | |||
Losing a private key means losing access to the bitcoins, with no other proof of ownership accepted by the ].<ref name=JEP/> For instance, in 2013, a user lost ₿7,500, valued at US$7.5 million, by accidentally discarding a ] with the private key.<ref>{{Cite news |date=29 November 2013 |title=Man Throws Away 7,500 Bitcoins, Now Worth $7.5 Million |work=CBS DC |url=http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |url-status=live |access-date=23 January 2014 |archive-url=https://web.archive.org/web/20140115062630/http://washington.cbslocal.com/2013/11/29/man-throws-away-7500-bitcoins-now-worth-7-5-million/ |archive-date=15 January 2014}}</ref> It is estimated that around 20% of all bitcoins are lost.<ref>{{Cite news |last=Krause |first=Elliott |date=5 July 2018 |title=A Fifth of All Bitcoin Is Missing. These Crypto Hunters Can Help |work=The Wall Street Journal |url=https://www.wsj.com/articles/a-fifth-of-all-bitcoin-is-missing-these-crypto-hunters-can-help-1530798731 |url-status=live |access-date=8 July 2018 |archive-url=https://web.archive.org/web/20180709010939/https://www.wsj.com/articles/a-fifth-of-all-bitcoin-is-missing-these-crypto-hunters-can-help-1530798731 |archive-date=9 July 2018}}</ref> The private key must also be kept secret as its exposure, such as through a ], can lead to theft of the associated bitcoins.<ref name="Antonopoulos2014" />{{rp|ch. 10}}<ref>{{Cite news |last=Jeffries |first=Adrianne |date=19 December 2013 |title=How to steal Bitcoin in three easy steps |work=The Verge |url=https://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps |url-status=live |access-date=17 January 2014 |archive-url=https://web.archive.org/web/20190727141228/https://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps |archive-date=27 July 2019}}</ref> {{As of|2017|12}}, approximately ₿980,000 had been stolen from ]s.<ref>{{Cite news |last1=Harney |first1=Alexandra |last2=Stecklow |first2=Steve |date=16 November 2017 |title=Twice burned – How Mt. Gox's bitcoin customers could lose again |work=Reuters |url=https://www.reuters.com/investigates/special-report/bitcoin-gox/ |url-status=live |access-date=6 September 2018 |archive-url=https://web.archive.org/web/20190829052101/https://www.reuters.com/investigates/special-report/bitcoin-gox/ |archive-date=29 August 2019}}</ref> | |||
In the United States two men were arrested in January 2014 on charges of money-laundering using bitcoins including ], the head of defunct bitcoin exchange ] and a vice chairman of the ]. Shrem allegedly allowed the other arrested party to purchase large quantities of bitcoins for use on black-market websites.<ref name=vchair/> | |||
===Mining=== | |||
In early February 2014, one of the largest bitcoin exchanges, ],<ref>{{cite web | url=http://www.bbc.com/news/technology-26420932 | title=MtGox gives bankruptcy details | publisher=BBC | work=bbc.com | date=4 March 2014 | accessdate=13 March 2014}}</ref> suspended withdrawals citing technical issues.<ref>{{cite web|url=http://techcrunch.com/2014/02/10/whats-going-on-with-bitcoin-exchange-mt-gox/ |title=What’s Going On With Bitcoin Exchange Mt. Gox? |first=John |last=Biggs |publisher=TechCrunch |date=10 February 2014|accessdate=26 February 2014}}</ref> By the end of the month, Mt. Gox had filed for bankruptcy protection in Japan amid reports that 744,000 bitcoins had been stolen.<ref name="GoxBankrupt">{{cite web | url=http://www.bbc.com/news/technology-25233230 | title=MtGox bitcoin exchange files for bankruptcy | publisher=BBC | work=bbc.com | date=28 February 2014 | accessdate=18 April 2014}}</ref> Originally a site for trading ] cards,<ref>{{cite web | url=http://blogs.wsj.com/five-things/2014/02/25/5-things-about-mt-goxs-crisis/ | title=Five Things About Mt. Gox's Crisis | publisher=Dow Jones and Company | work=The Wall Street Journal | date=25 Feb 2014 | accessdate=18 April 2014 | author=Vigna, Paul}}</ref> Mt. Gox once was the dominant bitcoin exchange although prior to the collapse its popularity had waned due largely to users having difficulty withdrawing funds.<ref>{{cite web | url=http://www.csmonitor.com/USA/USA-Update/2014/0228/MtGox-bankruptcy-Bitcoin-insiders-saw-problems-with-the-exchange-for-months | title=MtGox bankruptcy: Bitcoin insiders saw problems with the exchange for months | publisher=The Christian Science Monitor | work=csmonitor.com | date=28 February 2014 | accessdate=18 April 2014 | author=Swan, Noelle}}</ref> | |||
{{See also|Bitcoin protocol#Mining}} | |||
] with large amounts of mining hardware]] | |||
The mining process in bitcoin involves maintaining the blockchain through computer ]. Miners group and broadcast new transactions into blocks, which are then verified by the network.<ref name="econbc">{{Cite news |date=31 October 2015 |title=The great chain of being sure about things |newspaper=The Economist |url=https://www.economist.com/briefing/2015/10/31/the-great-chain-of-being-sure-about-things |access-date=22 November 2023 |archive-date=4 December 2023 |archive-url=https://web.archive.org/web/20231204154941/https://www.economist.com/briefing/2015/10/31/the-great-chain-of-being-sure-about-things |url-status=live }}</ref> Each block must contain a proof of work (PoW) to be accepted,<ref name="econbc" /> involving finding a ] number that, combined with the block content, produces a ] numerically smaller than the network's ''difficulty target''.<ref name="Antonopoulos2014" />{{rp|ch. 8}} This PoW is simple to verify but hard to generate, requiring many attempts.<ref name="Antonopoulos2014" />{{rp|ch. 8}} PoW forms the basis of bitcoin's ].<ref name=Mingxiao2017>{{Cite conference |last1=Mingxiao |first1=Du |last2=Xiaofeng |first2=Ma |last3=Zhe |first3=Zhang |last4=Xiangwei |first4=Wang |last5=Qijun |first5=Chen |date=5–8 October 2017 |title=A review on consensus algorithm of blockchain |url=https://ieeexplore.ieee.org/document/8123011 |publisher=IEEE |pages=2567–2572 |doi=10.1109/SMC.2017.8123011 |isbn=978-1-5386-1645-1 |conference=2017 IEEE International Conference on Systems, Man, and Cybernetics (SMC) |location=Banff, AB, Canada |access-date=29 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124215821/http://ieeexplore.ieee.org/document/8123011 |url-status=live }}</ref> | |||
The difficulty of generating a block is ] based on the ] by changing the difficulty target, which is recalibrated every 2,016 blocks (approximately two weeks) to maintain an average time of ten minutes between new blocks. The process requires significant computational power and specialized ].<ref name="Antonopoulos2014" />{{rp|ch. 8}}<ref>{{cite news |date=4 January 2014 |url=http://www.taipeitimes.com/News/biz/archives/2014/01/04/2003580449 |title=Bitcoin boom benefiting TSMC: report |newspaper=] |access-date=22 October 2021 |archive-date=29 January 2023 |archive-url=https://web.archive.org/web/20230129102127/https://www.taipeitimes.com/News/biz/archives/2014/01/04/2003580449 |url-status=live }}</ref> | |||
==Economics== | |||
Miners who successfully find a new block can collect transaction fees from the included transactions and a set reward in bitcoins.<ref name="bloombergvance111413">{{Cite magazine |last=Ashlee |first= Vance |author-link=Ashlee Vance |date=14 November 2013 |title=2014 Outlook: Bitcoin Mining Chips, a High-Tech Arms Race |url=http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |url-status=dead |magazine=] |archive-url=https://web.archive.org/web/20131121225123/http://www.businessweek.com/articles/2013-11-14/2014-outlook-bitcoin-mining-chips-a-high-tech-arms-race |archive-date=21 November 2013 |access-date=24 November 2013}}</ref> To claim this reward, a special transaction called a ''coinbase'' is included in the block, with the miner as the payee. All bitcoins in existence have been created through this type of transaction.<ref name="Antonopoulos2014" />{{rp|ch. 8}} This reward is halved every 210,000 blocks until ₿21 million,{{efn|name=supply|The exact number is ₿20,999,999.9769.{{r|Antonopoulos2014|page=ch. 8}}}} with new bitcoin issuance slated to end around 2140. Afterward, miners will only earn from transaction fees. These fees are determined by the transaction's size and the amount of data stored, measured in satoshis per byte.<ref>{{cite news |first1=Ritchie S. |last1=King |first2=Sam |last2=Williams |first3=David |last3=Yanofsky |date=17 December 2013 |title=By reading this article, you're mining bitcoins |url=http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins |work=] |access-date=17 December 2013 |archive-date=17 December 2013 |archive-url=https://web.archive.org/web/20131217221429/http://qz.com/154877/by-reading-this-page-you-are-mining-bitcoins/ |url-status=live }}</ref><ref name="EconOfBTC" /><ref name="Antonopoulos2014" />{{rp|ch. 8}} | |||
===Classification=== | |||
According to the director of the Institute for Money, Technology and Financial Inclusion at the ] there is "an unsettled debate about whether bitcoin is a currency or payment protocol".<ref name="currencydispute">{{cite web | url=http://www.usatoday.com/story/money/business/2014/04/25/ozy-bitcoin-africa-currency/8148853/ | title=How bitcoin is moving money in Africa | publisher=USA Today | work=usatoday.com | date=25 April 2014 | accessdate=25 May 2014 | author=Joyner, April}}</ref> Despite this, bitcoin is commonly referred to with terms like: digital currency,<ref name="primer" /> digital cash,<ref>{{cite web | url = http://www.nytimes.com/2013/08/01/technology/personaltech/virtual-currency-gains-ground-in-actual-world.html | title = Virtual Currency Gains Ground in Actual World | publisher = The New York Times | date = 31 July 2013 | accessdate = 6 May 2014 | author = Murphy, Kate | quote = "A type of digital cash, bitcoins were invented in 2009 and can be sent directly to anyone, anywhere in the world."}}</ref> virtual currency,<ref name="satoshi unit" /> electronic currency,<ref name="capitalization" /> or cryptocurrency.<ref name="currencydispute"/> Some media outlets do make a distinction between "real" money and bitcoins, however.<ref>{{cite web | url=http://www.bloombergview.com/articles/2013-11-29/building-better-bitcoins | title=Building Better Bitcoins | publisher=Bloomberg LP | work=Bloomberg View | date=29 Nov 2013 | accessdate=25 May 2014 | author=Carter, Stephen L. | quote=A principal knock on bitcoins has been the claim that they are inherently insecure. The principal defense has been that they are as secure as “real” currency. }}</ref> | |||
The proof of work system and the chaining of blocks make blockchain modifications very difficult, as altering one block requires changing all subsequent blocks. As more blocks are added, modifying older blocks becomes increasingly challenging.<ref>{{Cite news |last=Hampton |first=Nikolai |date=5 September 2016 |title=Understanding the blockchain hype: Why much of it is nothing more than snake oil and spin |work=] |url=http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |url-status=live |access-date=5 September 2016 |archive-url=https://web.archive.org/web/20160906171838/http://www.computerworld.com.au/article/606253/understanding-blockchain-hype-why-much-it-nothing-more-than-snake-oil-spin/ |archive-date=6 September 2016}}</ref><ref name="econbc" /> In case of disagreement, nodes trust the longest chain, which required the greatest amount of effort to produce.<ref name=Mingxiao2017/> To tamper or censor the ledger, one needs to control the majority of the global ].<ref name=Mingxiao2017/> The high cost required to reach this level of computational power ] the bitcoin blockchain.<ref name=Mingxiao2017/> | |||
Economists defining ] as a ], a ], and a ] agree that bitcoin has some way to go to meet all these criteria.<ref name=econ315 /> It does best as a medium of exchange.<ref name=econ315>{{cite news|title=Free Exchange. Money from nothing. Chronic deflation may keep Bitcoin from displacing its rivals.|url=http://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money|accessdate=25 March 2014|newspaper=The Economist|date=15 March 2014}}</ref> (About 1,000 ] businesses were willing to accept payment in bitcoins as of November 2013<ref name="bitcoin_brick_and_mortar_merchants">{{cite web |author=Joon Ian Wong |url=http://www.coindesk.com/surge-in-real-locations-accepting-bitcoin/ |title=CoinMap: Bitcoin-Accepting Merchants Increased 81% in November |publisher=CoinDesk |date=28 November 2013 |accessdate=1 December 2013}}</ref> in addition to more than 35,000 online merchants.){{refn | group = note | To obtain 35,000 figure, 16,000 merchants signed up with Bitcoin payment processor Coinbase<ref>{{cite web |url=http://techcrunch.com/2013/12/12/coinbase-raises-25m-from-andreessen-horowitz-to-build-its-bitcoin-wallet-and-merchant-services/ |title=Coinbase Raises $25M Led By Andreessen Horowitz To Build Its Bitcoin Wallet And Merchant Services |publisher=TechCrunch |author=Alex Williams |date=12 December 2013| accessdate=13 December 2013}}</ref> are added to 20,000 merchants signed to BitPay.<ref>{{cite web |url=http://www.coindesk.com/get-paid-bitcoin-bitpays-payroll-api/ |title=Get Paid in Bitcoin With BitPay’s New Payroll API |first=Jon |last=Southurst |date=14 January 2014|accessdate=17 January 2014|publisher=Coindesk}}</ref>}} The bitcoin market currently suffers from ], limiting the ability of bitcoins to act as a stable store of value,<ref name=econ315 /> and, although bitcoin is the unit of account for the block chain, bitcoin does not see use as a unit of account outside of it. Where people are allowed to buy with bitcoins, prices are not denominated in bitcoins.<ref name=econ315/> Even in online black markets, prices are stated in local currency although purchases are often made with bitcoins.<ref>{{cite web | url=http://www.bbc.com/news/technology-26147994 | title=Utopia drugs market forced off Tor by Dutch police | publisher=BBC | work=bbc.com | date=12 February 2014 | accessdate=10 November 2014}}</ref> | |||
] is controversial and has attracted the attention of regulators, ].<ref name=Stoll2023>{{Cite report |url=https://www.jstor.org/stable/resrep51839 |title=Climate Impacts of Bitcoin Mining in the U.S. |last1=Stoll |first1=Christian |last2=Klaaßen |first2=Lena |date=June 2023 |publisher=MIT Center for Energy and Environmental Policy Research |last3=Gallersdörfer |first3=Ulrich |last4=Neumüller |first4=Alexander |series=Working Paper Series |access-date=24 November 2023 |archive-date=18 November 2023 |archive-url=https://web.archive.org/web/20231118132421/https://www.jstor.org/stable/resrep51839 |url-status=live }}</ref> {{As of|2022}}, a ] study by the ] (CCAF) estimated that bitcoin mining represented {{sigfig|0.38|1}}% of ].<ref name=Messina2023>{{Cite web |last=Messina |first=Irene |date=31 August 2023 |title=Bitcoin electricity consumption: an improved assessment |url=https://www.jbs.cam.ac.uk/2023/bitcoin-electricity-consumption |access-date=7 September 2023 |website=] |language=en-GB |archive-date=7 September 2023 |archive-url=https://web.archive.org/web/20230907181818/https://www.jbs.cam.ac.uk/2023/bitcoin-electricity-consumption/ |url-status=live }}</ref> Another 2022 non-peer-reviewed commentary published in '']'' estimated that bitcoin mining was responsible for {{sigfig|0.19|1}}% of world greenhouse gas emissions.<ref name= deVries2022>{{Cite journal |last1=de Vries |first1=Alex |last2=Gallersdörfer |first2=Ulrich |last3=Klaaßen |first3=Lena |last4=Stoll |first4=Christian |date=16 March 2022 |title=Revisiting Bitcoin's carbon footprint |journal=] |volume=6 |issue=3 |page=499 |doi=10.1016/j.joule.2022.02.005 |s2cid=247143939 |issn=2542-4351|doi-access=free |bibcode=2022Joule...6..498D }}</ref> About half of the electricity used is generated through ]s.<ref name=NYT20220116>{{Cite news |last1=Huang |first1=Jon |last2=O'Neill |first2=Claire |last3=Tabuchi |first3=Hiroko |date=3 September 2021 |title=Bitcoin Uses More Electricity Than Many Countries. How Is That Possible? |work=] |url=https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |issn=0362-4331 |access-date=16 January 2022 |archive-date=17 February 2023 |archive-url=https://web.archive.org/web/20230217105559/https://www.nytimes.com/interactive/2021/09/03/climate/bitcoin-carbon-footprint-electricity.html |url-status=live }}</ref> Moreover, mining hardware's short lifespan results in ].<ref name=deVries2021/> The amount of electrical energy consumed, and the e-waste generated, is comparable to that of Greece and the Netherlands, respectively.<ref name=deVries2021>{{Cite journal |last1=de Vries |first1=Alex |last2=Stoll |first2=Christian |date=December 2021 |title=Bitcoin's growing e-waste problem |url=https://www.sciencedirect.com/science/article/pii/S0921344921005103 |journal=Resources, Conservation and Recycling |volume=175 |page=105901 |doi=10.1016/j.resconrec.2021.105901 |bibcode=2021RCR...17505901D |s2cid=240585651 |issn=0921-3449 |access-date=24 November 2023 |archive-date=23 November 2021 |archive-url=https://web.archive.org/web/20211123145025/https://www.sciencedirect.com/science/article/abs/pii/S0921344921005103 |url-status=live }}</ref><ref name= deVries2022/> | |||
Various government agencies, departments, and courts have classified bitcoins differently. Both the U.S. Treasury<ref name="JSC" /> and the European Central Bank<ref name="ECB" /> classify bitcoin as a virtual currency. The ] has stated that bitcoin "is fundamentally not a currency but an investment target".<ref name="bloomberg.com">{{cite web|url=http://www.bloomberg.com/news/2014-04-10/china-s-bitcoin-exchanges-say-banks-will-close-their-accounts.html|title=China’s Bitcoin Exchanges Say Banks Will Close Their Accounts|quote=The central bank will keep watching risks from Bitcoin, which is fundamentally not a currency but an investment target, Sheng Songcheng, head of the monetary authority’s statistics department, told reporters in Beijing on Jan. 15 2014.|newspaper= Bloomberg|date= 10 April 2014|accessdate=11 April 2014}}</ref> Magistrate Judge Amos L. Mazzant of ] classified bitcoins as a currency.<ref name="Ponzicase">{{cite court|litigants = SEC v. Trendon T. Shavers and Bitcoin Savings and Trust|vol = 416|court = E.D. Tex.|date = 2013|url= https://ia800904.us.archive.org/35/items/gov.uscourts.txed.146063/gov.uscourts.txed.146063.23.0.pdf}}</ref> A German court found bitcoin to be a ].<ref name=btcregs>{{cite web | url=http://www.loc.gov/law/help/bitcoin-survey/regulation-of-bitcoin.pdf| title=Regulation of Bitcoin in Selected Jurisdictions | publisher=The Law Library of Congress, Global Legal Research Center | date=January 2014 | accessdate=26 August 2014}}</ref> The Finnish government judged it to be a ].<ref>{{cite news | url = http://www.bloomberg.com/news/2014-01-19/bitcoin-becomes-commodity-in-finland-after-failing-currency-test.html | title = Bitcoin Judged Commodity in Finland After Failing Money Test | author = Kati Pohjanpalo | work = Bloomberg | location = New York | date = 20 January 2014 | accessdate = 27 January 2014}}</ref> | |||
===Privacy and fungibility=== | |||
Journalists and academics likewise lack unanimous agreement on what to call bitcoin. The Wall Street Journal declared it a commodity in December 2013.<ref>{{cite news | url = http://blogs.wsj.com/venturecapital/2013/12/12/with-25m-coinbase-to-push-bitcoin-from-commodity-to-currency/ | title = Coinbase to Push Bitcoin From Commodity to Currency, With $25M From Investors | publisher = The Wall Street Journal | date = 12 December 2013 | accessdate = 27 January 2014 | author = Chapman, Lizette}}</ref> A Forbes journalist referred to it as digital collectible.<ref>{{cite news | url = http://www.forbes.com/sites/louiswoodhill/2013/04/11/bitcoins-are-digital-collectibles-not-real-money/ | title = Bitcoins Are Digital Collectibles, Not Real Money | publisher = Forbes | date = 4 November 2013 | accessdate = 27 January 2014 | author = Woodhill, Louis}}</ref> Two ] computer scientists proposed the term "money-like informational commodity" in order "to allow for a systematic discussion of its development through all stages including an initial stage and a possible demise without being constrained by the implications of it being a money or a near-money".<ref name="mlic">{{cite web | url = http://arxiv.org/pdf/1402.4778.pdf|author=Bergstra, J. A., Weijland, P. | date = February 2014 | title = Bitcoin: a money-like informational commodity | publisher = Cornell University | journal = arXiv.org | issue = preprint arXiv:1402.4778. | pages = 26}}</ref> | |||
Bitcoin is ]ous, with funds linked to addresses, not real-world identities. While the owners of these addresses are not directly identified, all transactions are public on the blockchain. Patterns of use, like spending coins from multiple inputs, can hint at a common owner. Public data can sometimes be matched with known address owners.<ref>{{cite news |last=Simonite |first=Tom |date=5 September 2013 |title=Mapping the Bitcoin Economy Could Reveal Users' Identities |url=https://www.technologyreview.com/2013/09/05/176558/mapping-the-bitcoin-economy-could-reveal-users-identities/ |access-date=2 April 2014 |work=] |archive-date=27 September 2020 |archive-url=https://web.archive.org/web/20200927062235/https://www.technologyreview.com/2013/09/05/176558/mapping-the-bitcoin-economy-could-reveal-users-identities/ |url-status=live }}</ref> ] might also need to collect personal data as per legal requirements.<ref>{{Cite news |last=Lee, Timothy |date=21 August 2013 |title=Five surprising facts about Bitcoin |newspaper=The Washington Post |url=https://www.washingtonpost.com/news/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2 |access-date=21 November 2023 |archive-date=9 July 2022 |archive-url=https://web.archive.org/web/20220709135222/https://www.washingtonpost.com/news/the-switch/wp/2013/08/21/five-surprising-facts-about-bitcoin-2/ |url-status=live }}</ref> For enhanced ], users can generate a new address for each transaction.<ref>{{Cite magazine |last=McMillan, Robert |date=6 June 2013 |title=How Bitcoin lets you spy on careless companies |url=https://www.wired.com/2013/06/bitcoin-retai/ |url-status=live |archive-url=https://web.archive.org/web/20140209202222/http://www.wired.co.uk/news/archive/2013-06/06/bitcoin-retail |archive-date=9 February 2014 |access-date=3 April 2020 |magazine=] }}</ref> | |||
In the bitcoin network, each bitcoin is treated equally, ensuring basic ]. However, users and applications can choose to differentiate between bitcoins. While wallets and software treat all bitcoins the same, each bitcoin's transaction history is recorded on the blockchain. This public record allows for ], where users can identify and potentially reject bitcoins from controversial sources.<ref>{{Cite book |last1=Anderson |first1=Ross |last2=Shumailov |first2=Ilia |last3=Ahmed |first3=Mansoor |title=Security Protocols XXVI |chapter=Making Bitcoin Legal |series=Lecture Notes in Computer Science |date=24 November 2018 |volume=11286 |chapter-url=https://www.research.ed.ac.uk/en/publications/making-bitcoin-legal |language=en |publisher=Springer |pages=243–253 |doi=10.1007/978-3-030-03251-7_29 |isbn=978-3-030-03250-0 |editor-last=Matyáš |editor-first=Vashek |editor2-last=Švenda |editor2-first=Petr |editor3-last=Stajano |editor3-first=Frank |editor4-last=Christianson |editor4-first=Bruce |access-date=24 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124165246/https://www.research.ed.ac.uk/en/publications/making-bitcoin-legal |url-status=live }}</ref> For example, in 2012, Mt. Gox froze accounts containing bitcoins identified as stolen.<ref>{{Cite conference |last1=Möser |first1=Malte |last2=Böhme |first2=Rainer |last3=Breuker |first3=Dominic |year=2013 |title=An Inquiry into Money Laundering Tools in the Bitcoin Ecosystem |url=https://maltemoeser.de/paper/money-laundering.pdf |conference=2013 APWG eCrime Researchers Summit |publisher=] |isbn=978-1-4799-1158-5 |archive-url=https://web.archive.org/web/20180626110754/https://maltemoeser.de/paper/money-laundering.pdf |archive-date=26 June 2018 |access-date=19 June 2019 |url-status=live}}</ref> | |||
===Buying and selling=== | |||
Bitcoins can be bought and sold with many different currencies from individuals and companies. Bitcoins may be purchased in person<ref>{{cite web|author=Lauren Orsini |url=http://www.businessinsider.com/heres-what-happened-when-i-bought-bitcoin-in-person-2013-10 |title=Here's What Happened When I Bought Bitcoin In Person |publisher=Business Insider |date=23 October 2013|accessdate=4 February 2014}}</ref> or at a ] in exchange for ] currency.<ref>{{cite news | url = http://www.usatoday.com/story/money/business/2014/02/19/bitcoin-atm-austin/5623387/ | work = USA Today | date = 20 February 2014 | first = Rick | last = Jervis | title = Bitcoin ATMs come to USA | accessdate = 31 October 2014}}</ref> Participants in online ] offer bitcoin ]. Using an online exchange to obtain bitcoins entails some risk, and, according to one study, 45% of exchanges fail and take client bitcoins with them.<ref name="wired45">{{cite web |url= http://www.wired.co.uk/news/archive/2013-04/26/large-bitcoin-exchanges-attacks |title=Study: 45 percent of Bitcoin exchanges end up closing |date=26 April 2013|work=Wired |accessdate=28 April 2013|author=Steadman, Ian |deadurl=no}}</ref> Since bitcoin transactions are irreversible, sellers of bitcoins must take extra measures to ensure they have received traditional funds from the buyer. | |||
=== |
===Wallets=== | ||
{{Broader|Cryptocurrency wallet}} | |||
To improve access to price information and increase transparency, on 30 April 2014 ] announced plans to list prices from bitcoin companies Kraken and ] on its 320,000 subscription financial data terminals.<ref name=wsjprice>{{cite news|title=Bloomberg to List Bitcoin Prices, Offering Key Stamp of Approval|url=http://online.wsj.com/news/articles/SB10001424052702304893404579532471795644350?mg=reno64-wsj&url=http%3A%2F%2Fonline.wsj.com%2Farticle%2FSB10001424052702304893404579532471795644350.html|accessdate=1 May 2014|newspaper=WSJ|date=30 April 2014|author=Michael J. Casey}}</ref> | |||
{{multiple image | |||
| total_width = 600 | |||
| align = center | |||
| image1 = Bitcoin-core-v0.10.0.png | |||
| caption1 = Screenshot of ] | |||
| image2 = Sample Bitcoin paper wallet.png | |||
| caption2 = A paper wallet with the address as a ] while the private key is hidden | |||
| image3 = 10elqpi.jpg | |||
| caption3 = A hardware wallet which processes bitcoin transactions without exposing private keys | |||
}} | |||
Bitcoin wallets were the first ]s, enabling users to store the information necessary to transact bitcoins.<ref>{{cite news |first1=Adam |last1=Serwer |first2=Dana|last2= Liebelson |date=10 April 2013 |title=Bitcoin, Explained |url=https://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |url-status=live |archive-url=https://web.archive.org/web/20140427022315/https://www.motherjones.com/politics/2013/04/what-is-bitcoin-explained |archive-date=27 April 2014 |access-date=26 April 2014 |work=]}}</ref>{{r|Antonopoulos2014|p=ch. 1, glossary}} The first wallet program, simply named ''Bitcoin'', and sometimes referred to as the ''Satoshi client'', was released in 2009 by Nakamoto as ].<ref name="NY2011" /> ] is among the best known ]. ] of Bitcoin Core exist such as ].<ref>{{Cite news |last=Vigna |first=Paul |date=17 January 2016 |title=Is Bitcoin Breaking Up? |work=The Wall Street Journal |url=https://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |url-status=live |access-date=8 November 2016 |archive-url=https://web.archive.org/web/20160820144312/http://www.wsj.com/articles/is-bitcoin-breaking-up-1453044493 |archive-date=20 August 2016}}</ref> Wallets can be full clients, with a full copy of the blockchain to check the validity of mined blocks,{{r|Antonopoulos2014|p=ch. 1}} or lightweight clients, just to send and receive transactions without a local copy of the entire blockchain.<ref>{{Cite book |last1=Gervais |first1=Arthur |last2=Capkun |first2=Srdjan |last3=Karame |first3=Ghassan O. |last4=Gruber |first4=Damian |title=Proceedings of the 30th Annual Computer Security Applications Conference |chapter=On the privacy provisions of Bloom filters in lightweight bitcoin clients |date=8 December 2014 |chapter-url=https://doi.org/10.1145/2664243.2664267 |series=ACSAC '14 |location=New York, NY, USA |publisher=Association for Computing Machinery |pages=326–335 |doi=10.1145/2664243.2664267 |isbn=978-1-4503-3005-3 |s2cid=9161497 |access-date=22 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113526/https://consent.cookiebot.com/uc.js |url-status=live }}</ref> Third-party internet services called online wallets store users' credentials on their servers, making them susceptible of hacks.<ref>{{Cite news |first=Bill |last=Barhydt |date=4 June 2014 |title=3 reasons Wall Street can't stay away from bitcoin |publisher=CNBC |url=https://www.cnbc.com/2014/06/04/3-reasons-wall-street-cant-stay-away-from-bitcoin.html |access-date=22 November 2023 |archive-date=4 December 2023 |archive-url=https://web.archive.org/web/20231204140256/https://www.cnbc.com/2014/06/04/3-reasons-wall-street-cant-stay-away-from-bitcoin.html |url-status=live }}</ref> Cold storage protects bitcoins from such hacks by keeping private keys offline, either through specialized hardware wallets or paper printouts.<ref>{{Cite news |last=Roberts |first=Daniel |date=15 December 2017 |title=How to send bitcoin to a hardware wallet |work=Yahoo Finance |url=https://finance.yahoo.com/news/send-bitcoin-hardware-wallet-140141385.html |url-status=live |access-date=17 February 2018 |archive-url=https://web.archive.org/web/20180217142235/https://finance.yahoo.com/news/send-bitcoin-hardware-wallet-140141385.html |archive-date=17 February 2018}}</ref><ref name="Antonopoulos2014" />{{rp|ch. 4}} | |||
=== Scalability and decentralization challenges === | |||
According to ], bitcoin has the ] seven times greater than gold, eight times greater than the ], and eighteen times greater than the U.S. dollar.<ref>{{cite conference | url = http://management.bu.edu/files/2014/10/Wlliams-World-Bank-10-21-2014.pdf | title = Virtual Currencies – Bitcoin Risk | publisher = Boston University | booktitle = World Bank Conference Washington DC | date = 21 October 2014 | accessdate = 11 November 2014 | author = Williams, Mark T.}}</ref> According to Japanese scholars there is no stabilization mechanism.<ref>{{cite news | title = Japanese Scholars Draft Proposal for a Better Bitcoin | url = http://www.coindesk.com/japanese-scholars-draft-proposal-better-bitcoin/ | author = Nermin Hajdarbegovic | date = 7 November 2014 | accessdate = 8 November 2014 | publisher = CoinDesk}}</ref> The Bitcoin Foundation contends that high volatility is due to insufficient ],<ref>{{cite news|last=Wilkes |first=Tommy |url=http://www.reuters.com/article/2013/04/11/us-bitcoin-currency-idUSBRE93A0P020130411 |title=Backer defends virtual currency Bitcoin after big fall |publisher=Reuters |date= 11 April 2013|accessdate=7 January 2014}}</ref> while a Forbes journalist claims that it is related to the uncertainty of its long-term ].<ref>{{cite news |last=Lee |first=Timothy B. |title=Bitcoin Doesn't Have a Deflation Problem |url=http://www.forbes.com/sites/timothylee/2013/04/11/bitcoin-doesnt-have-a-deflation-problem/ |work=Forbes |location= |date=4 November 2013 |accessdate=27 January 2014}}</ref> As of 2014, pro-bitcoin venture capitalists argue the greatly increased trading volume that planned ] exchanges are hoped to bring, will decrease price volatility.<ref name=wsjprice /> Volatility has little effect on the utility of bitcoin as a payment processing system.<ref name="RooseNymag1113">{{cite web | last = Roose | first = Kevin | url = http://nymag.com/daily/intelligencer/2013/11/how-bitcoin-can-mainstream-in-one-easy-step.html | title = How Bitcoin Can Go Mainstream, in One Easy Step - Daily Intelligencer | publisher = Nymag.com | date = 21 November 2013 | accessdate = 25 November 2013}}</ref> | |||
Nakamoto limited the block size to one ].<ref>{{Cite news |last=Mike Orcutt |date=19 May 2015 |title=Leaderless Bitcoin Struggles to Make Its Most Crucial Decision |work=MIT Technology Review |url=https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |access-date=15 November 2016 |archive-date=18 October 2017 |archive-url=https://wayback.archive-it.org/all/20171018075515/https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |url-status=live }}</ref> The limited block size and frequency can lead to delayed processing of transactions, increased fees and a ].<ref>{{Cite news |last=Orcutt |first=Mike |date=19 May 2015 |title=Leaderless Bitcoin Struggles to Make Its Most Crucial Decision |work=MIT Technology Review |url=https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |url-status=live |access-date=22 June 2017 |archive-url=https://wayback.archive-it.org/all/20171018075515/https://www.technologyreview.com/s/537486/leaderless-bitcoin-struggles-to-make-its-most-crucial-decision/ |archive-date=18 October 2017}}</ref> The ], ] ] network, is a potential scaling solution.<ref name="Antonopoulos2014"/>{{rp|ch. 8}} | |||
Research shows a trend towards centralization in bitcoin as miners join ] for stable income.<ref name="JEP">{{Cite journal |last1=Rainer Böhme |last2=Nicolas Christin |last3=Benjamin Edelman |last4=Tyler Moore |year=2015 |title=Bitcoin: Economics, Technology, and Governance |journal=] |volume=29 |issue=2 |pages=213–238 |doi=10.1257/jep.29.2.213 |doi-access=free |issn=0895-3309}}</ref>{{rp|215, 219–222}}<ref>{{Cite journal |last1=Tschorsch |first1=Florian |last2=Scheuermann |first2=Björn |year=2016 |title=Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies |journal=] |volume=18 |issue=3 |pages=2084–2123 |doi=10.1109/comst.2016.2535718 |s2cid=5115101}}</ref>{{rp|3}} If a single miner or pool controls more than 50% of the ], it would allow them to censor transactions and double-spend coins.<ref name=Gervais2014/> In 2014, mining pool ] reached 51% mining power, causing safety concerns, but later voluntarily capped its power at 39.99% for the benefit of the whole network.<ref>{{Cite news |last=Wilhelm |first=Alex |title=Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared '51%' Fiasco |work=TechCrunch |url=https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/ |url-status=live |access-date=25 January 2018 |archive-url=https://web.archive.org/web/20171205042008/https://techcrunch.com/2014/07/16/popular-bitcoin-mining-pool-promises-to-restrict-its-compute-power-to-prevent-feared-51-fiasco/ |archive-date=5 December 2017}}</ref> A few entities also dominate other parts of the ecosystem such as the client software, online wallets, and simplified payment verification (SPV) clients.<ref name=Gervais2014/> | |||
The price of bitcoins has gone through various cycles of appreciation and depreciation referred to by some as ]s and busts.<ref>{{cite news|url=http://www.forbes.com/sites/jessecolombo/2013/12/19/bitcoin-may-be-following-this-classic-bubble-stages-chart/|title=Bitcoin May Be Following This Classic Bubble Stages Chart |publisher=Forbes |date=19 December 2013|accessdate=7 January 2014|first=Jesse |last=Colombo}}</ref><ref>{{cite web | url=http://www.theguardian.com/commentisfree/2013/apr/03/bitcoin-currency-bubble-crash-not-rocking-financial-markets | title=Confused about Bitcoin? It's 'the Harlem Shake of currency' | publisher=The Guardian | work=theguardian.com | date=3 April 2013 | accessdate=2 May 2014 | author=Moore, Heidi}}</ref> In 2011, the value of one bitcoin rapidly rose from about US$0.30 to US$32 before returning to US$2.<ref name="Leebubble">{{cite news|url=http://www.washingtonpost.com/blogs/the-switch/wp/2013/11/05/when-will-the-people-who-called-bitcoin-a-bubble-admit-they-were-wrong|title=When will the people who called Bitcoin a bubble admit they were wrong | publisher=The Washington Post|date=5 November 2013|accessdate=10 January 2014|author=Lee, Timothy}}</ref> In the latter half of 2012 and during the ], the bitcoin price began to rise,<ref>{{cite web|last=Liu |first=Alec |url=http://motherboard.vice.com/blog/cyprus-spain-when-governments-take-your-money-bitcoin-looks-really-good |title=When Governments Take Your Money, Bitcoin Looks Really Good |publisher=Motherboard|date=19 March 2013 |accessdate=7 January 2014}}</ref> reaching a peak of US$266 on 10 April 2013, before crashing to around US$50.<ref>{{cite news|url=http://www.forbes.com/sites/timothylee/2013/04/11/an-illustrated-history-of-bitcoin-crashes/ |title=An Illustrated History Of Bitcoin Crashes |publisher=Forbes |date= 11 April 2013|accessdate=7 January 2014|first=Timothy B. |last=Lee}}</ref> On November 29, 2013, the cost of one bitcoin rose to the all-time peak of US$1,242,<ref>{{cite web | url = http://money.cnn.com/2013/11/29/investing/bitcoin-gold/index.html | title = Bitcoin worth almost as much as gold | author = Ben Rooney | date = 29 November 2013 | publisher = CNN | accessdate = 31 October 2014}}</ref> but in 2014 the price fell sharply, and as of April remained depressed at little more than half 2013 prices. {{As of|2014|August}} it is under US$600, playing around US$580.<ref>{{cite web | url = http://www.nasdaq.com/article/bitcoin-prices-remain-below-600-amid-bearish-chart-signals-cm376685 | title = Bitcoin prices remain below $600 amid bearish chart signals | publisher = nasdaq.com | date = August 2014 | accessdate = 31 October 2014}}</ref> The Washington Post, however, pointed out that the observed cycles of appreciation and depreciation don't correspond to the definition of speculative bubble.<ref name="Leebubble" /> | |||
==Economics and usage== | |||
===Alternative to national currencies=== | |||
{{Main|Economics of bitcoin}} | |||
Bitcoins have been used by some Argentinians as an alternative to the official ],<ref>{{cite web | url = http://blogs.ft.com/beyond-brics/2013/04/16/bitcoins-gain-traction-in-argentina/ | title = Bitcoins gain traction in Argentina | author = Jude Webber | deadurl = no | publisher = Financial Times | date = 16 April 2013 | accessdate = 20 April 2013}}</ref> which is stymied by inflation and strict capital controls, to protect their savings against inflation or the possibility that governments could confiscate savings accounts.<ref name="5facts" /> During the ], bitcoin purchases rose due to fears that savings accounts would be confiscated or taxed.<ref name="BloombergCyprus">{{cite news | last = Salyer | first = Kirsten | title = Fleeing the Euro for Bitcoins | url = http://www.bloomberg.com/news/2013-03-20/fleeing-the-euro-for-bitcoins-.html | publisher = Bloomberg L.P.| date = 20 March 2013 | accessdate = 31 October 2014 | deadurl = no}}</ref> | |||
===Bitcoin's theoretical roots and ideology=== | |||
===Speculative bubble=== | |||
According to the ], the decentralization of money offered by bitcoin has its theoretical roots in the ], especially with ]'s '']'', in which he advocates a complete ] in the production, distribution and management of money to end the monopoly of ].<ref>{{cite book |author=European Central Bank |url=http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf |title=Virtual Currency Schemes |year=2012 |publisher=] |isbn=978-92-899-0862-7 |archive-url=https://web.archive.org/web/20121106053452/http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf |archive-date=6 November 2012 |url-status=live|oclc=1044382974|doi=10.2866/47380 }}</ref>{{rp|22}} Sociologist ] argues that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control.<ref>{{cite journal |last1=Dodd |first1=Nigel |date=May 2018 |title=The Social Life of Bitcoin |url=https://eprints.lse.ac.uk/69229/1/Dodd_The%20social%20life%20of%20Bitcoin_author_2017%20LSERO.pdf |journal=Theory, Culture & Society |volume=35 |issue=3 |pages=35–56 |doi=10.1177/0263276417746464 |s2cid=51914607 |issn=0263-2764 |authorlink1=Nigel Dodd |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163925/https://eprints.lse.ac.uk/69229/1/Dodd_The%20social%20life%20of%20Bitcoin_author_2017%20LSERO.pdf |url-status=live }}</ref> '']'' describes bitcoin as "a ] project to create an online version of cash, a way for people to transact without the possibility of interference from malicious governments or banks".<ref name="30082018Economist" /> These philosophical ideas initially attracted ]s and ]s.<ref>{{cite news |last=Feuer |first=Alan |date=14 December 2013 |title=The Bitcoin Ideology |work=The New York Times |url=https://www.nytimes.com/2013/12/15/sunday-review/the-bitcoin-ideology.html |url-status=live |access-date=1 July 2018 |archive-url=https://web.archive.org/web/20180701222302/https://www.nytimes.com/2013/12/15/sunday-review/the-bitcoin-ideology.html |archive-date=1 July 2018}}</ref> Economist ] argues that cryptocurrencies like bitcoin are only used by bank skeptics and criminals.{{r|Krugman}} | |||
Bitcoin has been labelled a ] by many including former ] ]<ref name=Kearns>{{cite news|url=http://www.bloomberg.com/news/2013-12-04/greenspan-says-bitcoin-a-bubble-without-intrinsic-currency-value.html|title=Greenspan Says Bitcoin a Bubble Without Intrinsic Currency Value|publisher=Bloomberg LP|work=bloomberg.com|date=4 December 2013|accessdate=23 December 2013|author=Kearns, Jeff}}</ref> and economist ].<ref name="BMH">{{cite news | url = http://nationalinterest.org/commentary/the-bitcoin-bubble-bad-hypothesis-8353 | title = The Bitcoin Bubble and a Bad Hypothesis | last = Quiggin | first = John | work = The National Interest | date = 16 April 2013 | deadurl = no | accessdate = 31 October 2014}}</ref> Two lead software developers of bitcoin, ]<ref>{{cite web | title = Bitcoin's History of Crushing Speculators | author = Dan Caplinger | publisher = ] | date = 4 April 2013 | accessdate = 7 January 2014 | url = http://www.fool.com/retirement/general/2013/04/04/bitcoins-history-of-crushing-speculators.aspx}}</ref> and Mike Hearn,<ref>{{cite news|url=http://www.bbc.co.uk/news/magazine-25332746|title=Bitcoin: Price v hype|publisher=BBC|work=bbc.com| date=13 December 2013|accessdate=23 December 2013 | author=Barford, Vanessa}}</ref> have warned that bubbles may occur. Nobel Laureate ] said that bitcoin "exhibited many of the characteristics of a ]".<ref>{{cite news | last = Shiller | first = Robert | title = In Search of a Stable Electronic Currency | url = http://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html?_r=0 | publisher = New York Times | date = 1 March 2014 | accessdate = 31 October 2014 | deadurl = no}}</ref> | |||
=== Recognition as a currency and legal status === | |||
David Andolfatto, a Vice President at the ] stated: "Is bitcoin a bubble? Yes, if ''bubble'' is defined as a liquidity premium." According to Andolfatto, most assets likely have a "bubble" component to their price, e.g., gold.<ref name="Andolfatto2014-03" /> ] analyst Matthew Boesler, rejects the "speculative bubble" label and sees bitcoin's quick rise in price as nothing more than normal economic forces at work.<ref>{{cite web | last = Boesler | first = Matthew | title = ANALYST: The Rise Of Bitcoin Teaches A Tremendous Lesson About Global Economics | url = http://www.businessinsider.com/global-economics-lesson-from-bitcoin-2013-3 | publisher = Business Insider | date = 7 March 2013 | accessdate = 31 October 2014 | deadurl = no}}</ref> | |||
{{Legal status of bitcoin|300px}} | |||
] serves three purposes: a ], a ], and a ].<ref name="econ315">{{Cite news |date=15 March 2014 |title=Free Exchange. Money from nothing. Chronic deflation may keep Bitcoin from displacing its rivals. |newspaper=The Economist |url=https://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |url-status=live |access-date=25 March 2014 |archive-url=https://web.archive.org/web/20140325085119/http://www.economist.com/news/finance-and-economics/21599053-chronic-deflation-may-keep-bitcoin-displacing-its-fiat-rivals-money |archive-date=25 March 2014}}</ref> According to ''The Economist'' in 2014, bitcoin functions best as a medium of exchange.<ref name=econ315 /> In 2015, ''The Economist'' noted that bitcoins had three qualities useful in a currency: they are "hard to earn, limited in supply and easy to verify".<ref>{{Cite news |date=13 January 2015 |title=The magic of mining |newspaper=] |url=https://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |url-status=live |access-date=13 January 2015 |archive-url=https://web.archive.org/web/20150112165531/http://www.economist.com/news/business/21638124-minting-digital-currency-has-become-big-ruthlessly-competitive-business-magic |archive-date=12 January 2015}}</ref> However, a 2018 assessment by ''The Economist'' stated that cryptocurrencies met none of these three criteria.<ref name="30082018Economist">{{Cite news |date=30 August 2018 |title=Bitcoin and other cryptocurrencies are useless |newspaper=The Economist |url=https://www.economist.com/leaders/2018/08/30/bitcoin-and-other-cryptocurrencies-are-useless |url-status=live |access-date=4 September 2018 |archive-url=https://web.archive.org/web/20180904040905/https://www.economist.com/leaders/2018/08/30/bitcoin-and-other-cryptocurrencies-are-useless |archive-date=4 September 2018 }}</ref> Per some researchers, {{as of|2015|lc=yes}}, bitcoin functions more as a ] than as a currency.<ref name=JEP/> In 2014, economist ] wrote that bitcoin has potential as a unit of account for measuring the relative value of goods, as with Chile's ], but that "Bitcoin in its present form... doesn't really solve any sensible economic problem".<ref name="Shiller">{{Cite news |last=Shiller |first=Robert |date=1 March 2014 |title=In Search of a Stable Electronic Currency |work=The New York Times |url=https://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html |url-status=live |archive-url=https://web.archive.org/web/20141024120222/http://www.nytimes.com/2014/03/02/business/in-search-of-a-stable-electronic-currency.html |archive-date=24 October 2014}}</ref> François R. Velde, Senior Economist at the ], described bitcoin as "an elegant solution to the problem of creating a digital currency".<ref>{{cite web |last=Velde |first=François |date=December 2013 |title=Bitcoin: A primer |url=https://www.chicagofed.org/digital_assets/publications/chicago_fed_letter/2013/cfldecember2013_317.pdf |url-status=live |archive-url=https://web.archive.org/web/20141026065254/http://www.chicagofed.org/digital_assets/publications/chicago_fed_letter/2013/cfldecember2013_317.pdf |archive-date=26 October 2014 |access-date=3 September 2016 |website=Chicago Fed letter |publisher=] |page=4 |issue=317}}</ref> David Andolfatto, Vice President at the ], stated that bitcoin is a threat to the establishment, which he argues is a good thing for the ] and other ]s, because it prompts these institutions to operate sound policies.<ref>{{cite news |last=Wile|first= Rob |date=6 April 2014 |title=St. Louis Fed Economist: Bitcoin Could Be A Good Threat To Central Banks |url=http://www.businessinsider.com/interview-with-david-andolfatto-2014-4 |url-status=live |archive-url=https://web.archive.org/web/20150924095030/http://www.businessinsider.com/interview-with-david-andolfatto-2014-4 |archive-date=24 September 2015 |access-date=16 April 2014 |work=]}}</ref> | |||
The ] varies substantially from one jurisdiction to another. Because of its decentralized nature and its global presence, regulating bitcoin is difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a ] ban.<ref>{{cite news |first=Jacob |last=Weindling |date=18 September 2017 |title=China May Be Gearing Up to Ban Bitcoin |url=https://www.pastemagazine.com/politics/bitcoin/china-may-be-gearing-up-to-ban-bitcoin |work=] |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.pastemagazine.com/politics/bitcoin/china-may-be-gearing-up-to-ban-bitcoin |url-status=live }}</ref> The ] has attracted the attention of financial regulators, legislative bodies, and law enforcement.<ref>{{Cite news |last=Lavin|first= Tim |date=8 August 2013 |title=The SEC Shows Why Bitcoin Is Doomed |work=] |url=http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |url-status=live |access-date=20 October 2013 |archive-url=https://web.archive.org/web/20140325214514/http://www.bloombergview.com/articles/2013-08-08/did-the-sec-just-validate-bitcoin-no- |archive-date=25 March 2014}}</ref> Nobel-prize winning economist ] says that bitcoin's anonymity encourages ] and other crimes.<ref>{{Cite news |last=Montag |first=Ali |date=9 July 2018 |title=Nobel-winning economist: Authorities will bring down 'hammer' on bitcoin |publisher=CNBC |url=https://www.cnbc.com/2018/07/09/nobel-prize-winning-economist-joseph-stiglitz-criticizes-bitcoin.html |url-status=live |access-date=11 July 2018 |archive-url=https://web.archive.org/web/20180711200915/https://www.cnbc.com/2018/07/09/nobel-prize-winning-economist-joseph-stiglitz-criticizes-bitcoin.html |archive-date=11 July 2018}}</ref> This is the main justification behind bitcoin bans.<ref name=SunYin2019/> {{As of|2021|11}}, nine countries applied an absolute ban (Algeria, Bangladesh, China, Egypt, Iraq, Morocco, Nepal, Qatar, and Tunisia) while another 42 countries had an implicit ban.<ref name=LOC2021>{{cite web |title=Regulation of Cryptocurrency Around the World: November 2021 Update |url=https://tile.loc.gov/storage-services/service/ll/llglrd/2021687419/2021687419.pdf |publisher=United States Library of Congress |access-date=28 December 2022 |archive-date=24 December 2021 |archive-url=https://web.archive.org/web/20211224043203/https://tile.loc.gov/storage-services/service/ll/llglrd/2021687419/2021687419.pdf |url-status=live }}</ref>{{Update inline|reason=Many things have changed since Nov 2021.|date=November 2023}} Bitcoin is only ] in ].<ref name=BTCSVSept7FT/> | |||
===As investment=== | |||
One way of investing in bitcoins is to buy and hold them as a long-term investment.<ref name="cnbc">{{cite web | url=http://www.cnbc.com/id/45030812/The_Pros_And_Cons_Of_Biting_on_Bitcoins|title=The Pros And Cons Of Biting on Bitcoins|publisher=]|date=23 November 2011|accessdate=4 December 2012|author=Gustke, Constance|deadurl=no}}</ref> The ] (FINRA), a United States ],<ref>{{cite news|url=http://www.reuters.com/article/2014/03/11/us-bitcoin-finra-idUSBREA2A1OJ20140311 |title= Beware Bitcoin: U.S. brokerage regulator.|author=Jonathan Stempel|date=11 March 2014|accessdate=14 March 2014|publisher=reuters.com}}</ref> and the ]<ref name="ebawarn">{{cite web|url=http://www.eba.europa.eu/documents/10180/16136/EBA+Warning+on+Virtual+Currencies.pdf|archiveurl=http://www.webcitation.org/6MCBOsSXG|archivedate=28 December 2013|title=Warning to consumers on virtual currencies|publisher=European Banking Authority |date=12 December 2013| accessdate=23 December 2013}}</ref> warned that investing in bitcoins carries significant risks. Risk hasn't deterred some such as the ], who in April 2013 claimed they owned nearly 1% of all bitcoins in existence at the time<ref>{{cite web | title = Never Mind Facebook; Winklevoss Twins Rule in Digital Money | author = Nathaniel Popper and Peter Lattman | url = http://dealbook.nytimes.com/2013/04/11/as-big-investors-emerge-bitcoin-gets-ready-for-its-close-up/ | publisher = ] | date = 11 April 2013 | accessdate = 31 October 2014}}</ref> and have since attempted to launch a bitcoin ].<ref name=winkles/> The first regulated bitcoin fund was established in Jersey in July 2014, with the approval of the Jersey Financial Services Commission.<ref name="BitcoinJersey">{{cite news|title=Jersey approve Bitcoin fund launch on island|url=http://www.bbc.com/news/world-europe-jersey-28247796|date=10 July 2014|accessdate=10 July 2014|publisher=BBC news}}</ref> Other investors, like ]'s ], which invested {{currency|3|USD}} million in ], do not purchase bitcoins themselves, instead funding bitcoin infrastructure like companies that provide payment systems to merchants, exchanges, wallet services, etc.<ref name="mtr20130612">{{cite news | url = http://www.technologyreview.com/news/515391/bitcoin-millionaires-become-investing-angels/ | title = Bitcoin Millionaires Become Investing Angels | work = Computing News | publisher = ] | date = 12 June 2013 | accessdate = 13 June 2013 | author = Simonite, Tom}}</ref> Investors also invest in bitcoin mining.<ref>{{cite news| url=http://www.redherring.com/finance/coinseed-raises-7-5m-invests-5m-in-bitcoin-mining-hardware-investment-round-up/| title=CoinSeed raises $7.5m, invests $5m in Bitcoin mining hardware – Investment Round Up|work=Red Herring|date=24 January 2014| accessdate=9 March 2014}}</ref> | |||
=== |
=== Use for payments === | ||
] accepting Bitcoin]] | |||
Financial journalists and analysts, economists, and investors have attempted to predict the possible future value of bitcoin. In April 2013, economist ] stated, "bitcoins will attain their true value of zero sooner or later, but it is impossible to say when",<ref name="BMH" /> a similar forecast was made in November 2014 by economist ].<ref>{{cite news | author = Kevin Dowd | title = Bitcoin is bust: Why investors should abandon the doomed cryptocurrency | url = http://www.cityam.com/1415215686/bitcoin-bust-why-investors-should-abandon-doomed-cryptocurrency | date = 5 November 2014 | accessdate = 6 November 2014 | work = Opinion | publisher = ]}}</ref> In May 2013, ] FX and Rate Strategist David Woo forecast a maximum fair value per bitcoin of $1,300.<ref name="BoAFA">{{cite news | last = Sharf | first = Samantha | title = Bitcoin Gets Valued: Bank Of America Puts A Price Target On The Virtual Tender | url = http://www.forbes.com/sites/samanthasharf/2013/12/05/bitcoin-gets-valued-bank-of-america-puts-a-price-on-the-virtual-tender/ | work = Forbes | location = New York | date = 12 May 2013 | accessdate = 31 October 2014}}</ref> Bitcoin investor ] stated in December 2013 that the "mall bull case scenario for bitcoin is... 40,000 USD a coin".<ref>{{cite news | last = Schroeder | first = Stan | title = Cameron Winklevoss: Bitcoin Might Hit $40,000 Per Coin | url = http://mashable.com/2013/12/16/cameron-winklevoss-bitcoin/ | work = Mashable | location = New York | date = 1 December 2013 | accessdate = 31 October 2014}}</ref> In December 2013, finance professor ] forecast a bitcoin would be worth less than ten U.S. dollars by July 2014.<ref>{{cite web | url=http://www.businessinsider.com/williams-bitcoin-meltdown-10-2013-12 | title=FINANCE PROFESSOR: Bitcoin Will Crash To $10 By Mid-2014 | publisher=Business Insider | work=businessinsider.com | date=17 December 2013|accessdate=26 February 2014|author=Williams, Mark T.}}</ref> Since then bitcoin has exchanged as low as $344 (April 2014) and during July 2014 the bitcoin low has been $609.<ref>{{cite web | url = https://blockchain.info/charts/market-price?showDataPoints=false&show_header=true&daysAverageString=1×pan=1year&scale=0&address= | title = Market Price (USD) | accessdate = 2 November 2014 | publisher = blockchain.info}}</ref> | |||
{{As of|2018}}, bitcoin is rarely used in transactions with merchants,<ref name="FT08062018" /> but it is popular to ] online.<ref name=TheEconomist20120929>{{Cite news |title=Monetarists Anonymous |newspaper=The Economist |url=https://www.economist.com/finance-and-economics/2012/09/29/monetarists-anonymous |date=29 September 2012 |access-date=22 November 2023 |issn=0013-0613 |archive-date=1 September 2022 |archive-url=https://web.archive.org/web/20220901043303/https://www.economist.com/finance-and-economics/2012/09/29/monetarists-anonymous |url-status=live }}</ref><ref>{{Cite news |last=Ball |first=James |date=22 March 2013 |title=Silk Road: the online drug marketplace that officials seem powerless to stop |language=en-GB |work=The Guardian |url=https://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |access-date=22 November 2023 |issn=0261-3077 |archive-date=12 October 2013 |archive-url=https://web.archive.org/web/20131012012106/http://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace |url-status=live }}</ref> Prices are not usually quoted in bitcoin and trades involve conversions into ] currencies.<ref name=JEP/> Commonly cited reasons for not using bitcoin include high costs, the inability to process ]s, high ], long transaction times, and ] (especially for small purchases).<ref name="FT08062018">{{Cite news |last=Murphy |first=Hannah |date=8 June 2018 |title=Who really owns bitcoin now? |work=Financial Times |url=https://www.ft.com/content/29259448-69b3-11e8-b6eb-4acfcfb08c11 |url-status=live |access-date=10 June 2018 |archive-url=https://web.archive.org/web/20180610051316/https://www.ft.com/content/29259448-69b3-11e8-b6eb-4acfcfb08c11 |archive-date=10 June 2018}}</ref><ref>{{cite news |last=Katz |first=Lily |date=12 July 2017 |title=Bitcoin Acceptance Among Retailers Is Low and Getting Lower |url=https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |url-status=live |archive-url=https://web.archive.org/web/20180125204553/https://www.bloomberg.com/news/articles/2017-07-12/bitcoin-acceptance-among-retailers-is-low-and-getting-lower |archive-date=25 January 2018 |access-date=25 January 2018 |work=Bloomberg News}}</ref> ''Bloomberg'' reported that bitcoin was being used for large-item purchases on the site ] and for cross-border payments to ]s.<ref>{{Cite news |last=Kharif |first=Olga |date=1 August 2018 |title=Bitcoin's Use in Commerce Keeps Falling Even as Volatility Eases |work=Bloomberg News|url=https://www.bloomberg.com/news/articles/2018-08-01/bitcoin-s-use-in-commerce-keeps-falling-even-as-volatility-eases |url-status=live |access-date=2 August 2018 |archive-url=https://web.archive.org/web/20180802073219/https://www.bloomberg.com/news/articles/2018-08-01/bitcoin-s-use-in-commerce-keeps-falling-even-as-volatility-eases |archive-date=2 August 2018}}</ref> {{As of|2015}}, there was little sign of bitcoin use in international ]s despite high fees charged by banks and ] who compete in this market.<ref name=JEP/><ref>{{Cite news |last=Chan |first=Bernice |date=16 January 2015 |title=Bitcoin transactions cut the cost of international money transfers |work=] |url=https://www.scmp.com/lifestyle/technology/article/1679904/bitcoin-transactions-cut-cost-international-money-transfers |url-status=live |access-date=31 May 2019 |archive-url=https://web.archive.org/web/20190531060301/https://www.scmp.com/lifestyle/technology/article/1679904/bitcoin-transactions-cut-cost-international-money-transfers |archive-date=31 May 2019}}</ref> Despite associated risks and costs, in 2022, a growing use of bitcoin, alongside cash and cards, was reported in restaurant business.<ref>{{Cite web |url=https://www.nbcnews.com/business/bitcoin-bitcoin-restaurants-start-accept-cryptocurrencies-rcna21211 |title=Bitcoin by bitcoin, restaurants start to accept cryptocurrencies |date=2022-04-11 |access-date=2024-10-07 |website=NBC News |last=Sheidlower |first=Noah}}</ref> | |||
In September 2021, the ] made bitcoin ] in ], alongside the US dollar.<ref name=BTCSVSept7FT/> The adoption has been criticized internationally and within El Salvador.<ref name=BTCSVSept7FT/><ref>{{cite news |date=2 September 2021 |title=Majority of Salvadorans do not want bitcoin, poll shows |url=https://www.reuters.com/technology/majority-salvadorans-do-not-want-bitcoin-poll-shows-2021-09-02/ |access-date=30 November 2021 |work=Reuters |archive-date=30 November 2021 |archive-url=https://web.archive.org/web/20211130154620/https://www.reuters.com/technology/majority-salvadorans-do-not-want-bitcoin-poll-shows-2021-09-02/ |url-status=live }}</ref> In 2022, the ] (IMF) urged El Salvador to reverse its decision.<ref>{{cite news |date=26 January 2022 |title=IMF urges El Salvador to remove Bitcoin as legal tender |work=BBC News |url=https://www.bbc.co.uk/news/world-latin-america-60135552 |access-date=26 January 2022 |archive-date=26 January 2022 |archive-url=https://web.archive.org/web/20220126154241/https://www.bbc.co.uk/news/world-latin-america-60135552 |url-status=live }}</ref> {{As of|2022}}, the use of ] remains low: 80% of businesses refused to accept it.<ref>{{cite report |title=Are Cryptocurrencies Currencies? Bitcoin as Legal Tender in El Salvador |last1=Alvarez |first1=Fernando |last2=Argente |first2=David |publisher=National Bureau of Economic Research |doi=10.3386/w29968 |page= |last3=Van Patten |first3=Diana |doi-access=free |publication-place=Cambridge, MA |year=2022}}</ref> In April 2022, the ] (CAR) adopted bitcoin as legal tender alongside the ],<ref>{{Cite news |date=28 April 2022 |title=Bitcoin Declared Legal Currency in Central African Republic |work=Bloomberg |url=https://www.bloomberg.com/news/articles/2022-04-28/bitcoin-is-declared-a-legal-currency-in-central-african-republic-l2isppnb |access-date=28 April 2022 |archive-date=28 April 2022 |archive-url=https://web.archive.org/web/20220428141222/https://www.bloomberg.com/news/articles/2022-04-28/bitcoin-is-declared-a-legal-currency-in-central-african-republic-l2isppnb |url-status=live }}</ref> but repealed the reform one year later.<ref>{{Cite web |title=Frequently Asked Questions on Central African Republic |url=https://www.imf.org/en/Countries/CAF/central-african-republic-qandas |access-date=11 August 2023 |website=International Monetary Fund |language=en |archive-date=11 August 2023 |archive-url=https://web.archive.org/web/20230811002905/https://www.imf.org/en/Countries/CAF/central-african-republic-qandas |url-status=live }}</ref> | |||
===Reception=== | |||
Some economists have responded positively to bitcoin, but many have not. François R. Velde, Senior Economist at the ] described it as "an elegant solution to the problem of creating a digital currency".<ref>{{cite web | url = https://www.chicagofed.org/digital_assets/publications/chicago_fed_letter/2013/cfldecember2013_317.pdf | title = Bitcoin: A primer | date = December 2013 | accessdate = December 2013 | first = François | last = Velde | work = Chicago Fed letter | issue = 317 | pages = 4 | publisher = ]}}</ref> According to ] "in the estimation of many leading economists, bitcoin is a fatally flawed idea shaped by people who don’t really understand how money works".<ref>{{Cite web|url = http://www.wired.com/2014/02/rise-fall-rise-patrick-byrne/|title = Meet Patrick Byrne: Bitcoin Messiah, CEO of Overstock, Scourge of Wall Street|date = 10 February 2014|accessdate = 16 July 2014|website = Wired|publisher = Wired|last = Metz|first = Cade}}</ref> ] and ] have found fault with bitcoin questioning why it should act as a reasonably stable ] or whether there is a floor on its value.<ref>{{cite news |author= Paul Krugman |date= 28 December 2013 |title= Bitcoin Is Evil |url= http://krugman.blogs.nytimes.com/2013/12/28/bitcoin-is-evil/ |publisher= ] |accessdate= 28 December 2013 }}</ref> Economist ] has criticized bitcoin as "the final refutation of the ]".<ref name="BMH"/> | |||
Bitcoin is also used by some governments. For instance, the ] initially opposed cryptocurrencies, but later saw them as an opportunity to circumvent ].<ref>{{cite news |date=3 November 2020 |title=Iran Is Pivoting to Bitcoin |url=https://www.vice.com/en/article/qjppx3/iran-bitcoin-us-sanctions |work=] |last=Rasool |first=Mohammed |access-date=10 November 2020 |archive-date=3 November 2020 |archive-url=https://web.archive.org/web/20201103235640/https://www.vice.com/en/article/qjppx3/iran-bitcoin-us-sanctions |url-status=live }}</ref> Since 2020, Iran has required local bitcoin miners to sell bitcoin to the ], allowing the central bank to use it for imports.<ref name="aawsat202011">{{cite news |date=31 October 2020 |title=Iran: New Crypto Law Requires Selling Bitcoin Directly to Central Bank to Fund Imports |url=https://english.aawsat.com/home/article/2596686/iran-new-crypto-law-requires-selling-bitcoin-directly-central-bank-fund-imports |work=] |access-date=31 October 2020 |archive-date=31 October 2020 |archive-url=https://web.archive.org/web/20201031235032/https://english.aawsat.com/home/article/2596686/iran-new-crypto-law-requires-selling-bitcoin-directly-central-bank-fund-imports |url-status=live }}</ref> Some ] also accept tax payments in bitcoin, including ] (])<ref>{{Cite news |date=21 September 2022 |title=Colorado accepts cryptocurrency to pay taxes, moving the state "tech forward" |url=https://www.denverpost.com/2022/09/21/colorado-accepts-cryptocurrency-taxes/ |first=Judith |last=Kohler |work=] |language=en-US |access-date=29 December 2022 |archive-date=29 December 2022 |archive-url=https://web.archive.org/web/20221229090417/https://www.denverpost.com/2022/09/21/colorado-accepts-cryptocurrency-taxes/ |url-status=live }}</ref> and ] (]).<ref>{{Cite news |date=3 September 2020 |title='Crypto Valley' canton to accept Bitcoin for tax payments |url=https://www.swissinfo.ch/eng/business/-crypto-valley--canton-to-accept-bitcoin-for-tax-payments/46010364 |work=] |language=en |access-date=22 November 2023 |archive-date=22 November 2023 |archive-url=https://web.archive.org/web/20231122163924/https://www.swissinfo.ch/eng/business/-crypto-valley--canton-to-accept-bitcoin-for-tax-payments/46010364 |url-status=live }}</ref> As of 2023, the US government owned more than $5 billion worth of seized bitcoin.<ref>{{Cite news |last=Huang |first=Vicky Ge |title=Why the U.S. Government Has $5 Billion in Bitcoin |url=https://www.wsj.com/finance/currencies/federal-government-bitcoin-5-billion-78ce0938 |date=15 October 2023 |work=] |language=en-US |access-date=20 February 2024 |archive-date=20 February 2024 |archive-url=https://web.archive.org/web/20240220023509/https://www.wsj.com/finance/currencies/federal-government-bitcoin-5-billion-78ce0938 |url-status=live }}</ref><ref>{{Cite news |last=Castillo |first=Michael del |title=U.S. Government Owns Way More Bitcoin Than Any Other Country–So Why Aren't They Selling It? |url=https://www.forbes.com/sites/michaeldelcastillo/2023/06/16/us-government-owns-way-more-bitcoin-than-any-other-countryso-why-arent-they-selling-it |date=16 June 2023 |website=] |language=en |access-date=21 February 2024 |archive-date=21 February 2024 |archive-url=https://web.archive.org/web/20240221155659/https://www.forbes.com/sites/michaeldelcastillo/2023/06/16/us-government-owns-way-more-bitcoin-than-any-other-countryso-why-arent-they-selling-it/ |url-status=live }}</ref> | |||
David Andolfatto, a Vice President at the ], stated that bitcoin is a threat to the establishment, which he argues is a good thing for the Federal Reserve System and other central banks because it prompts these institutions to operate sound policies.<ref name="Andolfatto2014-03">{{cite web | url=http://www.stlouisfed.org/dialogue-with-the-fed/assets/Bitcoin-3-31-14.pdf | title=Bitcoin and Beyond: The Possibilities and Pitfalls of Virtual Currencies | publisher=Federal Reserve Bank of St. Louis | work=Dialogue with the Fed | date=31 March 2014 | accessdate=16 April 2014 | quote= Well-run central banks should welcome the emerging competition. There is (in my view) room for beneficial coexistence.| author=Andolfatto, David}}</ref><ref>{{cite web | url=http://www.businessinsider.com/interview-with-david-andolfatto-2014-4 | title=St. Louis Fed Economist: Bitcoin Could Be A Good Threat To Central Banks | publisher=Business Insider | work=businessinsider.com | date=6 April 2014 | accessdate=16 April 2014 | author=Wile, Rob}}</ref><ref>{{cite web | url=http://andolfatto.blogspot.com/2013/12/in-gold-we-trust.html | title=In gold we trust? | publisher=David Andolfatto | work=MacroMania | date=24 December 2013 | accessdate=17 April 2014 | quote=Also, note that I am not against gold or bitcoin (or whatever) as a currency. In fact, I think that the threat that they pose as alternate currency can serve as a useful check on a central bank. |author=Andolfatto, David}}</ref> | |||
===Use for investment and status as an economic bubble === | |||
] activist ] has criticized the lack of anonymity and called for reformed development.<ref>{{cite news|url=http://www.telegraph.co.uk/technology/news/10488201/Software-activist-calls-for-truly-anonymous-Bitcoins-to-protect-democracy.html |title=Software activist calls for 'truly anonymous' Bitcoins to 'protect democracy' |publisher=Telegraph |date= 2 December 2013|accessdate=27 December 2013|location=London |first=Matthew |last=Sparkes}}</ref> ] President ] calls bitcoin a "great place to put assets" but claims it will not be a currency until price volatility is reduced.<ref>{{cite web |url= http://news.cnet.com/8301-1023_3-57615080-93/paypal-president-david-marcus-bitcoin-is-good-nfc-is-bad/ |title= PayPal president David Marcus: Bitcoin is good, NFC is bad |date= 10 December 2013 |accessdate= 10 December 2013 |first= Stephen |last= Shankland |work= CNET}}</ref> | |||
{{Further|Cryptocurrency bubble}} | |||
] | |||
{{As of|2018}}, the overwhelming majority of bitcoin transactions took place on ]s.<ref name="FT08062018" /> Since 2014, regulated bitcoin funds also allow ] to the asset or to ] as an investment.<ref>{{Cite news |date=10 July 2014 |title=Jersey approve Bitcoin fund launch on island |work=BBC News |url=https://www.bbc.com/news/world-europe-jersey-28247796 |url-status=live |access-date=10 July 2014 |archive-url=https://web.archive.org/web/20140710211917/http://www.bbc.com/news/world-europe-jersey-28247796 |archive-date=10 July 2014}}</ref><ref>{{Cite news |date=18 December 2017 |title=Chicago Mercantile Exchange jumps into bitcoin futures |work=CBS News |url=https://www.cbsnews.com/news/chicago-mercantile-exchange-jumps-into-bitcoin-futures/ |url-status=live |access-date=31 May 2019 |archive-url=https://web.archive.org/web/20190531054602/https://www.cbsnews.com/news/chicago-mercantile-exchange-jumps-into-bitcoin-futures/ |archive-date=31 May 2019}}</ref> Bitcoin is used as a ]:<ref>{{Cite news |date=2021-10-25 |title=Gold or Bitcoin? Store-of-value debate rages as Bitcoin grows |url=https://www.bloomberg.com/professional/insights/trading/gold-or-bitcoin-store-of-value-debate-rages-as-bitcoin-grows/ |access-date=2024-10-02 |work=Bloomberg Professional Services |language=en-US}}</ref><ref>{{cite news|url=https://www.reuters.com/business/finance/goldman-sachs-says-bitcoin-will-compete-with-gold-store-value-2022-01-05/|title=Goldman Sachs says bitcoin will compete with gold as "store of value"|website=Reuters|date=2022-01-05}}</ref> individuals and companies such as the ]<ref>{{Cite news |last=Lee |first=Timothy B. |title=The $11 million in bitcoins the Winklevoss brothers bought is now worth $32 million |newspaper=The Washington Post |url=https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |url-status=live |access-date=11 August 2017 |archive-url=https://web.archive.org/web/20170706111658/https://www.washingtonpost.com/news/the-switch/wp/2013/11/09/the-11-million-in-bitcoins-the-winklevoss-brothers-bought-is-now-worth-32-million/ |archive-date=6 July 2017}}</ref> and ]'s companies ] and ] have massively invested in bitcoin.<ref>{{cite news |last1=Maidenberg |first1=Micah |last2=Driebusch |first2=Corrie |last3=Jin |first3=Berber |title=A Rare Look Into the Finances of Elon Musk's Secretive SpaceX |url=https://www.wsj.com/tech/behind-the-curtain-of-elon-musks-secretive-spacex-revenue-growth-and-rising-costs-2c828e2b |access-date=19 November 2023 |work=The Wall Street Journal |date=17 August 2023 |url-access=subscription |archive-date=17 August 2023 |archive-url=https://archive.today/20230817224420/https://www.wsj.com/tech/behind-the-curtain-of-elon-musks-secretive-spacex-revenue-growth-and-rising-costs-2c828e2b |url-status=live }}</ref><ref>{{Cite news |last1=Ostroff |first1=Caitlin |last2=Elliott |first2=Rebecca |date=8 February 2021 |title=Tesla Buys $1.5 Billion in Bitcoin |language=en-US |work=] |url=https://www.wsj.com/articles/tesla-buys-1-5-billion-in-bitcoin-11612791688 |access-date=22 November 2023 |issn=0099-9660 |url-access=subscription |archive-date=6 January 2024 |archive-url=https://web.archive.org/web/20240106160013/https://www.wsj.com/articles/tesla-buys-1-5-billion-in-bitcoin-11612791688 |url-status=live }}</ref> Bitcoin wealth is highly concentrated, with 0.01% holding 27% of in-circulation currency, as of 2021.<ref>{{Cite news |last1=Vigna |first1=Paul |title=Bitcoin's 'One Percent' Controls Lion's Share of the Cryptocurrency's Wealth |work=] |date=20 December 2021 |url=https://www.wsj.com/articles/bitcoins-one-percent-controls-lions-share-of-the-cryptocurrencys-wealth-11639996204 |issn=0099-9660 |url-access=subscription |access-date=22 December 2021 |archive-date=22 December 2021 |archive-url=https://web.archive.org/web/20211222180909/https://www.wsj.com/articles/bitcoins-one-percent-controls-lions-share-of-the-cryptocurrencys-wealth-11639996204 |url-status=live }}</ref> {{As of|2023|9}}, El Salvador had $76.5 million worth of bitcoin in its ].<ref>{{Cite news |last=Cota |first=Isabella |date=2 September 2023 |title=Two years of bitcoin in Bukele's El Salvador: An opaque experiment with a little-used currency |url=https://english.elpais.com/international/2023-09-02/two-years-of-bitcoin-in-bukeles-el-salvador-an-opaque-experiment-with-a-little-used-currency.html |website=] |language=en-us |access-date=24 November 2023 |archive-date=24 November 2023 |archive-url=https://web.archive.org/web/20231124082557/https://english.elpais.com/international/2023-09-02/two-years-of-bitcoin-in-bukeles-el-salvador-an-opaque-experiment-with-a-little-used-currency.html |url-status=live }}</ref> | |||
In 2018, research published in the '']'' concluded that ] occurred during the ] bitcoin theft and that the market remained vulnerable to manipulation.<ref>{{cite journal |last1=Gandal |first1=Neil |last2=Hamrick |first2=J.T. |last3=Moore |first3=Tyler |last4=Oberman |first4=Tali |date=May 2018 |title=Price manipulation in the Bitcoin ecosystem |journal=] |volume=95 |pages=86–96 |doi=10.1016/j.jmoneco.2017.12.004 |s2cid=26358036 |doi-access=free}}</ref> Research published in '']'' also suggested that trading associated with increases in the amount of the ] and associated trading at the ] exchange accounted for about half of the price increase in bitcoin in late 2017.<ref>{{Cite journal |last1=Griffin |first1=John M. |last2=Shams |first2=Amin |date=August 2020 |title=Is Bitcoin Really Untethered? |url= |journal=] |language=en |volume=75 |issue=4 |pages=1913–1964 |doi=10.1111/jofi.12903 |doi-access=free|s2cid=229576274 |issn=0022-1082}}</ref><ref>{{Cite news |last=Popper |first=Nathaniel |date=13 June 2018 |title=Bitcoin's Price Was Artificially Inflated Last Year, Researchers Say |work=The New York Times |url=https://www.nytimes.com/2018/06/13/technology/bitcoin-price-manipulation.html |url-status=live |access-date=13 June 2018 |archive-url=https://web.archive.org/web/20180613100732/https://www.nytimes.com/2018/06/13/technology/bitcoin-price-manipulation.html |archive-date=13 June 2018}}</ref> | |||
===Acceptance by merchants=== | |||
] in the ] as of 2013]] | |||
{{as of|2014|August}} established firms that accept payments in bitcoin include ],<ref name="powersellersunite.com"/> ],<ref>{{cite web|url=http://finance.yahoo.com/news/clearly-canadian-joins-bitcoin-community-110000013.html|title=Clearly Canadian Joins Bitcoin Community|work=finance.yahoo.com|date=23 December 2013|accessdate=10 February 2014|publisher=]}}</ref> ],<ref name=Dell>{{cite web | url = http://dealbook.nytimes.com/2014/07/18/dell-begins-accepting-bitcoin/ | title = Dell Begins Accepting Bitcoin | author = Sydney Ember | work = New York Times | date = 18 July 2014 | accessdate = 18 July 2014}}</ref> ], ],<ref>{{cite web | url=http://blogs.wsj.com/moneybeat/2014/06/11/expedia-starts-accepting-bitcoin-for-hotel-bookings/ | title = Expedia Starts Accepting Bitcoin for Hotel Bookings | author = Paul Vigna | work = Money Beat | publisher = The Wall Street Journal | date = 11 June 2014 | accessdate = 27 July 2014}}</ref> ],<ref>{{cite web|url=http://www.newegg.com/bitcoin|title=Newegg accepts bitcoins|work=newegg.com|date=1 July 2014|accessdate=3 July 2014}}</ref> ],<ref>{{cite web |url= http://www.telegraph.co.uk/technology/news/10558191/Ten-places-where-you-can-spend-your-bitcoins-in-the-UK.html |title= Ten places where you can spend your bitcoins in the UK |date= 10 January 2014|accessdate= 10 September 2013|first= Matthew|last= Sparkes|work= The Telegraph}}</ref> ],<ref name=overstock>{{cite web | url=http://blogs.marketwatch.com/thetell/2014/01/09/bitcoin-now-accepted-on-overstock-com-through-vc-backed-coinbase/ | title=Bitcoin now accepted on Overstock.com through VC-backed Coinbase|publisher=Wall Street Journal | work=marketwatch.com | date =9 January 2014|accessdate=10 February 2014|author=Vaishampayan, Saumya}}</ref> the ],<ref>{{cite news|url=http://www.bloomberg.com/news/2014-01-16/how-many-bitcoins-for-a-courtside-seat-.html|title=How Many Bitcoins for a Courtside Seat?|publisher=Bloomberg LP|work=bloomberg.com|date=16 Jan 2014|accessdate=20 January 2014|author=Davidson, Kavitha}}</ref> ],<ref name=tigger>{{cite web|url=http://www.tomshardware.com/news/tigerdirect-bitcoin-bitpay-payments,25859.html|title=TigerDirect is Now Accepting Bitcoin As Payment|publisher=Tom's hardware|date=26 January 2014| accessdate=28 August 2014|author=Jane McEntegart}}</ref> ],<ref>{{cite web |url= http://www.theguardian.com/technology/2013/nov/22/virgin-galactic-bitcoin-space-flights-payment |title= Virgin Galactic to accept Bitcoin for space flights |date= 22 November 2013|accessdate= 24 November 2013|first= Amanda|last= Holpuch |work= The Guardian}}</ref> and ].<ref>{{cite news|url=http://www.bloomberg.com/news/2014-01-05/bitcoin-tops-1-000-again-on-adoption-by-zynga-amid-wider-usage.html|title=Bitcoin Tops $1,000 Again as Zynga Accepts Virtual Money | publisher=Bloomberg LP | work=bloomberg.com | date=6 Jan 2014|accessdate=20 January 2014|author=Kharif, Olga}}</ref><ref group="note" name="processors" /> | |||
Bitcoin, along with other cryptocurrencies, has been described as an ] by several economists, including ] laureates, such as ],<ref name="Stiglitz">{{Cite news |last=Costelloe |first=Kevin |date=29 November 2017 |title=Bitcoin 'Ought to Be Outlawed,' Nobel Prize Winner Stiglitz Says |work=Bloomberg News |url=https://www.bloomberg.com/news/articles/2017-11-29/bitcoin-ought-to-be-outlawed-nobel-prize-winner-stiglitz-says-jal10hxd |url-status=live |access-date=5 June 2018 |archive-url=https://web.archive.org/web/20180612224313/https://www.bloomberg.com/news/articles/2017-11-29/bitcoin-ought-to-be-outlawed-nobel-prize-winner-stiglitz-says-jal10hxd |archive-date=12 June 2018 |quote=It doesn't serve any socially useful function. |url-access=subscription}}</ref> ],<ref name=4Nobels/> and ].<ref name=Krugman>{{Cite news |last=Mohamed |first=Theron |title=Nobel economist Paul Krugman slams crypto as mostly useless, after saying it's hugely overpriced and helps criminals |url=https://markets.businessinsider.com/news/currencies/paul-krugman-crypto-bitcoin-price-bubble-crime-cbdc-desantis-banks-2023-5 |date=30 May 2023 |website=] |language=en-US |access-date=23 November 2023 |archive-date=23 November 2023 |archive-url=https://web.archive.org/web/20231123131322/https://markets.businessinsider.com/news/currencies/paul-krugman-crypto-bitcoin-price-bubble-crime-cbdc-desantis-banks-2023-5 |url-status=live }}</ref> Another recipient of the prize, ], argues that bitcoin is rather a ] that may become an ]. He describes its price growth as an "epidemic", driven by ].<ref>{{Cite news |date=9 June 2021 |title=Don't Call Bitcoin a Bubble. It's an Epidemic |language=en |work=Bloomberg.com |url=https://www.bloomberg.com/opinion/articles/2021-06-09/don-t-call-bitcoin-a-bubble-it-s-an-epidemic |first=John |last=Authers|author-link=John Authers|archive-url=https://web.archive.org/web/20210610021335/https://www.bloomberg.com/opinion/articles/2021-06-09/don-t-call-bitcoin-a-bubble-it-s-an-epidemic |archive-date=10 June 2021 |url-status=live |url-access=subscription}}</ref> In 2024, ], also Nobel laureate, described bitcoin as a "pure bubble" as its ] is zero. According to him, some bubbles are long-lasting such as gold and fiat currencies, and it's impossible to predict whether bitcoin will collapse like other financial bubbles or become the new gold.<ref>{{Cite news |date=2024-02-01 |title=Cryptocurrencies: an economist's view |url=https://www.tse-fr.eu/cryptocurrencies-economists-view |access-date=2024-11-15 |language=en | first1=Jean|last1=Tirole|author-link1=Jean Tirole|work=La Jaune et la Rouge|issue=792|volume=February 2024}}</ref> The same year, ] ] described bitcoin as a digital competitor to gold but not to the dollar as he argued it is a highly volatile ] asset not used as a form of payment.<ref>{{Cite news |author= |date= |title=Bitcoin breaks $100,000 barrier amid post-election cryptocurrency surge |url=https://www.washingtonpost.com/business/2024/12/04/bitcoin-price-100k-crypto-trump/ |access-date=5 December 2024 |newspaper=Washington Post |quote=“People use bitcoin as a speculative asset. It’s like gold, it’s just like gold, only it’s virtual, it’s digital. People are not using it as a form of payment or a store of value,” he said. “It’s highly volatile. It’s not a competitor for the dollar; it’s really a competitor for gold.”}}</ref> | |||
In late 2013 the ] became the first university in the world to accept bitcoins.<ref>{{cite news|url= http://blogs.wsj.com/moneybeat/2013/11/22/the-university-of-bitcoin-rises-in-cyprus/ |title= The University of Bitcoin Rises in Cyprus|date= 22 November 2013|accessdate= 22 November 2013|first= Paul|last= Vigna|work= The Wall Street Journal}}</ref> | |||
According to research published in the '']'' in 2018, bitcoin as an asset is highly volatile and does not behave like any other conventional asset.<ref>{{Cite journal |last1=Klein |first1=Tony |last2=Pham Thu |first2=Hien |last3=Walther |first3=Thomas |date=October 2018 |title=Bitcoin is not the New Gold – A comparison of volatility, correlation, and portfolio performance |url=https://pureadmin.qub.ac.uk/ws/files/155247201/crypto_V2.pdf |journal=International Review of Financial Analysis |language=en |volume=59 |pages=105–116 |doi=10.1016/j.irfa.2018.07.010 |s2cid=158400153 |doi-access= |access-date=24 November 2023 |archive-date=25 November 2023 |archive-url=https://web.archive.org/web/20231125164037/https://pureadmin.qub.ac.uk/ws/files/155247201/crypto_V2.pdf |url-status=live }}</ref> According to one 2022 analysis published in '']'', bitcoin was less volatile than ], ], ], and 190 stocks in the ] during and after the ].<ref>{{Cite journal |last=Mazur |first=Mieszko |date=31 March 2022 |title=Misperceptions of Bitcoin Volatility |url= |journal=The Journal of Alternative Investments |language=en |volume=24 |issue=4 |pages=33–44 |doi=10.3905/jai.2022.1.153 |s2cid=247843794 |issn=1520-3255 |doi-access=}}</ref> The term {{wikt-lang|en|hodl}} was created in December 2013 for ] bitcoin rather than selling it during periods of volatility.<ref>{{cite news |last1=Montag |first1=Ali |title='HODL,' 'whale' and 5 other cryptocurrency slang terms explained |url=https://www.cnbc.com/2018/01/23/what-hodl-whale-and-other-cryptocurrency-slang-terms-mean.html |work=CNBC |date=26 August 2018 |access-date=16 March 2021 |archive-date=12 January 2022 |archive-url=https://web.archive.org/web/20220112091630/https://www.cnbc.com/2018/01/23/what-hodl-whale-and-other-cryptocurrency-slang-terms-mean.html |url-status=live }}</ref><ref>{{Cite news |url=https://www.bloomberg.com/news/articles/2020-11-19/what-the-heck-is-hodl-bitcoin-lingo-for-crypto-noobs-quicktake |title=All the Bitcoin Lingo You Need to Know as Crypto Heats Up |last=Hajric |first=Vildana |date=19 November 2020 |work=Bloomberg |access-date=1 December 2020 |url-access=subscription |archive-date=29 November 2020 |archive-url=https://web.archive.org/web/20201129234847/https://www.bloomberg.com/news/articles/2020-11-19/what-the-heck-is-hodl-bitcoin-lingo-for-crypto-noobs-quicktake |url-status=live }}</ref> | |||
As of 30 July 2014 the ], hoster of Misplaced Pages, offers the possibility of making donations to it in bitcoin (through Coinbase) on their donations page.<ref>{{cite web | url = http://blog.wikimedia.org/2014/07/30/wikimedia-foundation-now-accepts-bitcoin/ | title = Wikimedia Foundation Now Accepts Bitcoin | publisher = Wikimedia | author = Lisa Gruwell | date = 30 July 2014 | accessdate = 30 October 2014}}</ref> As of 22 September 2014 ] offers the possibility of making donations to it in bitcoin (through Bitpay).<ref>{{cite web | url = http://greenpeaceblogs.org/2014/09/22/greenpeace-now-accepting-bitcoin-donations/ | title = Greenpeace now accepting bitcoin donations | author = Cassady Sharp | date = 22 September 2014 | accessdate = 31 October 2014 | publisher = Greenpeace}}</ref> | |||
Other economists, investors, and the ] have described bitcoin as a potential ].<ref>{{cite news |last=Clinch |first=Matt |date=10 March 2014 |title=Roubini launches stinging attack on bitcoin |url=https://www.cnbc.com/2014/03/10/nches-stinging-attack-on-bitcoin.html |publisher=] |access-date=22 November 2023 |archive-date=9 July 2022 |archive-url=https://web.archive.org/web/20220709232801/https://www.cnbc.com/2014/03/10/nches-stinging-attack-on-bitcoin.html |url-status=live }}</ref><ref>{{cite news |title=This Billionaire Just Called Bitcoin a 'Pyramid Scheme' |work=]|url=https://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme |url-status=live |archive-url=https://web.archive.org/web/20170924045918/http://fortune.com/2017/07/27/howard-marks-bitcoin-pyramid-scheme/ |archive-date=24 September 2017 |access-date=23 September 2017}}</ref><ref>{{cite news |last1=Ott Ummelas |last2=Milda Seputyte |date=31 January 2014 |title=Bitcoin 'Ponzi' Concern Sparks Warning From Estonia Bank |work=Bloomberg News |url=https://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |url-status=live |access-date=1 April 2014 |archive-url=https://web.archive.org/web/20140329214501/http://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html |archive-date=29 March 2014 |url-access=subscription}}</ref> Legal scholar ] disagrees, however, as "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective ]".<ref>{{Cite news |last=Posner |first=Eric |author-link=Eric Posner |date=11 April 2013 |title=Fool's Gold |language=en-US |work=Slate |url=https://slate.com/news-and-politics/2013/04/bitcoin-is-a-ponzi-scheme-the-internet-currency-will-collapse.html |access-date=22 November 2023 |issn=1091-2339 |archive-date=8 July 2022 |archive-url=https://web.archive.org/web/20220708202651/https://slate.com/news-and-politics/2013/04/bitcoin-is-a-ponzi-scheme-the-internet-currency-will-collapse.html |url-status=live }}</ref> A 2014 ] report also concluded that bitcoin was not a deliberate Ponzi scheme.<ref>{{Cite book |last1=Davradakis |first1=Emmanouil |last2=Santos |first2=Ricardo |url=https://data.europa.eu/doi/10.2867/11329 |title=Blockchain, FinTechs and their relevance for international financial institutions |date=2019 |publisher=] |doi=10.2867/11329 |isbn=978-92-861-4184-3 |access-date=24 November 2023 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421113801/https://op.europa.eu/en/publication-detail/-/publication/ae472145-237a-11e9-8d04-01aa75ed71a1/language-en |url-status=live }}</ref> | |||
As of 23 September 2014 ] offers its North American merchants the possibility to receive customer payments for digital goods in bitcoin.<ref>{{cite web | url = https://www.paypal-community.com/t5/PayPal-Forward/PayPal-and-Virtual-Currency/ba-p/828230 | author = Scott Ellison | title = PayPal and Virtual Currency | date = 23 September 2014 | accessdate = 31 October 2014 | publisher = PayPal}}</ref> | |||
===Financial institutions=== | |||
As of 2014, bitcoin companies have had difficulty opening traditional bank accounts because lenders have been leery of bitcoin's links to illicit activity.<ref name=scaredbankers>{{cite web | url=http://www.bloomberg.com/news/2013-12-05/bitcoin-skepticism-by-bankers-from-china-to-u-s-hinders-growth.html | title=Bankers Balking at Bitcoin in U.S. as Real-World Obstacles Mount | publisher=Bloomberg | work=bloomberg.com | date=5 December 2013 | accessdate=16 April 2014 | author=Dougherty, Carter}}</ref> According to a co-founder of one such company, ], "banks are scared to deal with bitcoin companies, even if they really want to".<ref name=scaredbankers/> | |||
Yet, some financial institutions have been bullish on bitcoin. In a 2013 report, Bank of America Merrill Lynch stated that "we believe bitcoin can become a major means of payment for e-commerce and may emerge as a serious competitor to traditional money-transfer providers. As a medium of exchange, bitcoin has clear potential for growth and that in a long-term fair-value analysis maximum market capitalization for bitcoins could be $15 billion".<ref name=ForbesDec>{{cite news|last=Hill|first=Kashmir|title=Bitcoin Valued At $1300 By Bank of America Analysts|url=http://www.forbes.com/sites/kashmirhill/2013/12/05/bank-of-america-analysts-say-bitcoins-value-is-1300/|accessdate=23 March 2014|newspaper=Forbes.com|date=5 December 2013}}</ref> In June 2014, the first bank that converts deposits in currencies instantly to bitcoin without any fees, for further transactions, was opened in Boston.<ref>{{cite news|title=Bitcoin: is Circle the world's first crypto-currency bank?|url=http://www.theweek.co.uk/world-news/bitcoin/56138/bitcoin-passes-1000-mark-will-it-take-over-world|accessdate=13 June 2014|work=The week.co.uk|date=16 May 2014}}</ref> | |||
Concurrent with Bloomberg LP, 33% owned by Merrill Lynch launching pricing information is the development of ] firms by Atlas ATS in New York and Hong Kong and one from London-based ], claiming to be the first auditable bitcoin exchange, and a ] project of an exchange for institutional investors.<ref name=wsjprice /> | |||
A U.S. government auction of almost 30,000 bitcoins seized in October 2013 from the ] on 30 June 2014 by the ] was said to increase legitimacy of the currency. The 45 registered bidders, each of whom put down a deposit of $200,000 made 63 bids.<ref>{{cite news | title = Silk Road's legacy 30,000 bitcoin sold at auction to mystery buyers | author = Alex Hern | url = http://www.theguardian.com/technology/2014/jul/01/silk-road-bitcoin-auction | publisher = The Guardian | date = 1 July 2014 | accessdate = 31 October 2014}}</ref> | |||
According to David Andolfatto, a Vice President at the Federal Reserve Bank of St. Louis, bitcoin "Will force traditional institutions to adapt or die."<ref name="Andolfatto2014-03" /> | |||
===Political economy=== | |||
Bitcoin appeals to tech-savvy ]s, because it so far exists outside of the institutional banking system and the control of governments.<ref name=nation>{{cite news|url=http://www.thenation.com/article/179620/bitcoin-future-money?page=full| title=Bitcoin the Future of Money?|author=Doug Henwood|date=19 May 2014|publisher=The Nation.com|accessdate=12 September 2014}}</ref> | |||
Its appeal reaches from ], "who perceive the state and banking sector as representing the same elite interests, recognising in it the potential for collective ] governance of currency"<ref>{{cite web | url = http://www.e-ir.info/2014/06/01/visions-of-a-techno-leviathan-the-politics-of-the-bitcoin-blockchain/ | title = Visions of a Techno-Leviathan: The Politics of the Bitcoin Blockchain | author = Brett Scott | date = 1 June 2014 | publisher = E-International Relations | accessdate = 31 October 2014}}</ref> and socialists proposing their "own states, complete with currencies",<ref>{{cite web | url = http://internationalsocialistnetwork.org/index.php/ideas-and-arguments/301-mistress-magpie-a-left-defence-of-bitcoin | title = A left defence of Bitcoin | publisher = International Socialist Network | date = December 2013 | author = Margaret Corvid | accessdate = 31 October 2014}}</ref> to right wing critics suspicious of ], at a time when activities within the regulated banking system were responsible for the severity of the ],<ref>{{cite web | url = http://ssrn.com/abstract=2218812 | author = Melanie L. Fein | title = The Shadow Banking Charade | date = 15 February 2013 | accessdate = 31 October 2014}}</ref> "because governments are not fully living up to the responsibility that comes with state-sponsored money".<ref>{{cite news | url = http://www.breakingviews.com/edward-hadas-bitcoin-is-a-step-back-not-forward/21121998.article | title = Right-wing dreams | author = Edward Hadas | date = 27 November 2013 | publisher = Thomson Reuters | accessdate = 31 October 2014}}</ref> | |||
Bitcoin has been described as "remov the imbalance between the big boys of finance and the disenfranchised little man, potentially allowing early adopters to negotiate favourable rates on exchanges and transfers – something that only the very biggest firms have traditionally enjoyed".<ref>{{cite news|last1=Hamill|first1=Jasper|title=Native American Activist Wants To Swap The Dollar For Bitcoin|url=http://www.forbes.com/sites/jasperhamill/2013/12/19/native-american-activist-wants-to-swap-the-dollar-for-bitcoin/|accessdate=1 October 2014|work=Forbes| date=19 December 2013}}</ref> | |||
==Legal status and regulation== | |||
{{main|Legality of Bitcoin by country|l1=Legality of bitcoin by country}} | |||
Few governments have moved to regulate bitcoin and similar private currencies. | |||
According to the ], traditional financial sector regulation is not applicable because bitcoin does not involve traditional financial actors.<ref name=ECB>{{cite book|title=Virtual Currency Schemes|date=October 2012|publisher=European Central Bank|location=Frankfurt am Main|isbn=978-92-899-0862-7|page=5|url=http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf|format=PDF|author=European Central Bank|accessdate=5 March 2014|chapter=1}}</ref> Under other regimes, existing rules have been extended to include bitcoin and bitcoin companies. Steven Strauss, a Harvard public policy professor, suggested in April 2013 that governments could outlaw bitcoin,<ref>{{cite news|url=http://www.huffingtonpost.com/steven-strauss/bitcoin_b_3081812.html|title=Nine Trust-Based Problems With Bitcoin | work=The Huffington Post|date=14 April 2013|accessdate=20 October 2013 | last=Strauss | first=Steven}}</ref> a possibility that was mentioned in a 2013 ] filing made by a bitcoin investment vehicle.<ref name=winkles /> A detailed survey of forty foreign jurisdictions and the European Union is maintained by the ].<ref name=btcregs /> | |||
===China=== | |||
On 5 December 2013, ] made its first step in regulating bitcoin by prohibiting its financial institutions to handle bitcoin websites, requiring to report investors' identities to regulators and to start prohibiting money laundering.<ref name="Bloomberd">{{cite web|url=http://www.bloomberg.com/news/2013-12-05/china-s-pboc-bans-financial-companies-from-bitcoin-transactions.html |title=China Bans Financial Companies From Bitcoin Transactions |publisher=Bloomberg |date=5 December 2013 |accessdate=16 December 2013}}</ref><ref name=cnn>{{cite news|author1=Charles Riley|author2=Zhang Dayu|title=China cracks down on Bitcoin|url=http://money.cnn.com/2013/12/05/investing/china-bitcoin/|accessdate=8 November 2014|work=CNN money|publisher=Time Warner|date=December 5, 2013}}</ref> In a statement on the central bank’s website the ] said financial institutions and payment companies cannot give pricing in, buy and sell bitcoin or insure bitcoin-linked products. A December 2013 statement from BTC China suggested payment processors had voluntarily withdrawn their services.<ref>{{cite web|url=http://allthingsd.com/20131219/china-bitcoin-exchange-ceo-were-not-giving-up-yet/|title=China Bitcoin Exchange CEO: We’re Not Giving Up Yet |date=19 December 2013 |work=allthingsd.com|accessdate=19 December 2013}}</ref> On 1 April 2014 China Central Bank ordered commercial banks and payment companies to close bitcoin trading accounts in two weeks.<ref name=wsj4-2014>{{cite news|author1=Chao Deng|author2=Lingling Wei|title=China Cracks Down on Bitcoin|url=http://online.wsj.com/articles/SB10001424052702304157204579475233879506454|accessdate=8 November 2014|work=WSJ.com|publisher=Dow Jones & Company|date=1 April 2014}}</ref> Trading bitcoins by individuals is legal in China.<ref name="Bloomberd"/><ref>http://www.bbc.co.uk/news/technology-25428866</ref> | |||
===European Union=== | |||
In July 2014 the ] advised European banks not to deal in virtual currencies such as bitcoin until a regulatory regime was in place.<ref name=EBA>{{cite web|title=EBA Opinion on ‘virtual currencies|url=http://www.eba.europa.eu/documents/10180/657547/EBA-Op-2014-08+Opinion+on+Virtual+Currencies.pdf|publisher=European Banking Authority|accessdate=8 July 2014|pages=46|format=pdf|date=4 July 2014}}</ref> | |||
===G7=== | |||
The 2013 ]'s ] published guidance for Internet-based payment services that defines "exchangers buying or selling digital currency for cash (or other digital currencies) as a virtual bureau de change" and warns that "Internet-based payment services that allow third party funding from anonymous sources may face an increased risk of " concluding that this may "pose challenges to countries in regulation and supervision".<ref name=fatf>{{cite web|url=http://www.fatf-gafi.org/media/fatf/documents/recommendations/Guidance-RBA-NPPS.pdf|title=Guidance for a Risk-Based Approach: Prepaid Cards, Mobile Payments and Internet-based Payment Services|work=Guidance for a risk-based approach|publisher=Financial Action Task Force (FATF)|accessdate=6 March 2014|location=Paris|page=47|format=PDF|date=June 2013}}</ref> | |||
===USA=== | |||
The ] (GAO) reviewed virtual currencies upon the request of the ] and in May 2013 recommended<ref>{{cite web | url = http://www.gao.gov/products/gao-13-516 | title = Virtual Economies and currencies: Additional IRS guidance could reduce tax compliance risks | work = GAO Report GAO-13-516 | publisher = Report to the Committee on Finance, U.S. Senate | accessdate = 6 March 2014 | author = US Government Accountability Office | authorlink = Government Accountability Office | date = May 2013}}</ref> that the ] (IRS) formulate tax guidance for bitcoin businesses. On 25 March 2014, in time for 2013 tax filing, the IRS issued a guidance that virtual currency is treated as property for U.S. federal tax purposes and that "an individual who 'mines' virtual currency as a trade or business subject to self-employment tax".<ref name=IRS>{{cite web|title= IRS Virtual Currency Guidance|url=http://www.irs.gov/pub/irs-drop/n-14-21.pdf|work=Notice 2014-21|publisher=IRS|accessdate=30 March 2014|author=IRS|date=25 March 2014}}</ref> | |||
The U.S. ] stated in March 2014 it was considering regulation of digital currencies.<ref>{{cite news|title=U.S. swaps watchdog says considering bitcoin regulation|url=http://www.reuters.com/article/2014/03/11/us-bitcoin-regulation-idUSBREA2A1W020140311|accessdate=11 March 2014|newspaper=Reuters.com|date=11 March 2014|first=Douwe|last=Miedema}}</ref> | |||
In January 2014, the U.S. ] (SEC) was focused on whether bitcoin-denominated stock exchanges were illegal, per its enforcement administrator, and inquired into the gambling site SatoshiDice listing shares on bitcoin exchange MPEx.<ref>{{cite news|last1=Dougherty|first1=Carter|title=Gambling Website’s Bitcoin-Denominated Stock Draws SEC Inquiry|url=http://www.businessweek.com/news/2014-03-19/gambling-website-s-bitcoin-denominated-stock-draws-sec-inquiry|accessdate=13 June 2014|work=Bloomberg BusinessWeek.com|publisher=Bloomberg LP|date=20 March 2014}}</ref> In May it warned investors that "both fraudsters and promoters of high-risk investment schemes may target bitcoin users".<ref>{{cite web|title=Investor Alert: Bitcoin and Other Virtual Currency-Related Investments|url=http://investor.gov/news-alerts/investor-alerts/investor-alert-bitcoin-other-virtual-currency-related-investments#.U3GCQ61dVD4|work=Investor.gov|publisher=U.S. Securities and Exchange Commission|accessdate=13 May 2014}}</ref> The SEC charged and settled with the former owner of SatoshiDice in June 2014 for selling securities without registering with the SEC.<ref>{{cite web|title=Press Release SEC Charges Bitcoin Entrepreneur With Offering Unregistered Securities|url=http://www.sec.gov/News/PressRelease/Detail/PressRelease/1370541972520#.U5qaD3bb73C|publisher=SEC.gov|accessdate=13 June 2014|date=3 June 2014}}</ref> | |||
On 8 May 2014, the U.S. ] issued draft guidance to U.S. politicians who want to receive bitcoin donations.<ref name="ADVISORY OPINION 2014-02">{{cite web | url=http://saos.fec.gov/aodocs/2014-02.pdf | title=FEC Advisory Opinion 2014-02 | publisher=Federal Election Commission | date=8 May 2014 | accessdate=8 May 2014 | author=Goodman, Lee E. }}</ref> The Commission declined to declare bitcoins currency, stating they fit into its "anything of value" definition.<ref>{{cite news |url=https://www.publicintegrity.org/2014/05/08/14739/what-fecs-bitcoin-ruling-means | title=What the FEC's Bitcoin ruling means |date=8 May 2014 |accessdate=8 May 2014 |first=Dave |last=Levinthal |work=Center for Public Integrity}}</ref> | |||
On 18 November 2013, the ] held a committee hearing titled ''Beyond Silk Road: Potential Risks, Threats and Promises of Virtual Currencies'' to discuss virtual currencies.<ref name="theguardian">{{cite web |url= http://www.theguardian.com/technology/2013/nov/18/bitcoin-risks-rewards-senate-hearing-virtual-currency |title= Bitcoin hits $700 high as Senate stages hearing on virtual currency |date= 18 November 2013 |accessdate= 24 November 2013 |first= Dominic |last= Rushe |work= The Guardian}}</ref> At this hearing, held by senator ], bitcoin and other currencies were received generally positively, with it being stated that bitcoin was a "legal means of exchange" and that "online payment systems, both centralized and decentralized, offer legitimate financial services" by US officials such as Peter Kadzik and ].<ref name="raskin">{{cite web |url= http://www.bloomberg.com/news/2013-11-18/u-s-agencies-to-say-bitcoins-offer-legitimate-benefits.html |title= U.S. Agencies to Say Bitcoins Offer Legitimate Benefits |date= 18 November 2013 |accessdate= 24 November 2013 |first= Max |last= Raskin |work= Bloomberg}}</ref><ref>{{cite web |url= http://www.washingtonpost.com/business/economy/for-bitcoin-a-successful-charm-offensive-on-the-hill/2013/11/22/000ed4b0-53b1-11e3-a7f0-b790929232e1_story.html |title= For Bitcoin, a successful charm offensive on the Hill |date= 23 November 2013 |accessdate= 24 November 2013 |first= Timothy |last= Lee |work= Washington Post}}</ref> It was noted, however, that the Justice Department's Criminal Division has seen an increased use of virtual currencies for illegal purposes such as drugs and child pornography.<ref>{{cite web |url= http://www.bbc.co.uk/news/technology-24986264 |title= 'Legitimate' Bitcoin's value soars after Senate hearing |date= 19 November 2013 |accessdate= 24 November 2013 |work= BBC News}}</ref> | |||
The FEC deadlocked on Nov 21, 2013 on whether to allow bitcoin in political campaigns.<ref name="fecbitcoin">{{cite web|last=Gillum |first=Jack |url=http://bigstory.ap.org/article/fec-donors-cant-use-bitcoins-contributions |title=FEC: Donors can't use bitcoins for contributions |publisher=Bigstory.ap.org |date=2013-04-03 |accessdate=2013-12-27}}</ref> Their decision was split across party lines (three members Democrat voting nay, three Republicans voting yay). While their decision covered group donations, political bitcoin pioneers New Hampshire House member Mark Warden<ref name="wardenbtc">{{cite web | url = http://www.markwarden.com/page/contribute-campaign | title = Donate to the campaign | Mark Warden — State Rep | publisher = Markwarden.com | date = | accessdate = 9 November 2014}}</ref> and Southern California politician Michael B. Glenn<ref name="latimesbitcoin">{{cite web | last = Foxhall | first = Emily | url = http://www.latimes.com/local/lanow/la-me-ln-bitcoin-accepted-newport-city-council-race-20131220,0,7500678.story | title = Bitcoin donations welcome, Newport Beach City Council candidate says | publisher = latimes.com | date = 20 December 2013 | accessdate = 27 December 2013}}</ref> acted independently in accepting bitcoin, and paved the way for others to follow suit. | |||
In May 2014, Brett Stapper, co-founder of Falcon Global Capital, registered to lobby members of Congress and federal agencies on issues related to bitcoin.<ref name="Bitcoin gets a lobbyist">{{cite web | url=http://thehill.com/policy/technology/207085-bitcoin-investors-register-lobbyist?nr_email_referer=1%29 | title=Bitcoin gets a lobbyist | publisher=The Hill | date=23 May 2014 | accessdate=27 May 2014 | author=Hattem, Julian}}</ref> | |||
In June 2014 California Assemblyman ] (D–Sacramento) submitted draft legislation to legalize bitcoin and all other forms of alternative and digital currency.<ref name="BitcoinCalifornia">{{cite web | url=http://www.businessinsider.com/bitcoin-llegal-in-california-2014-6?utm_source=alerts&nr_email_referer=1 | title=Bitcoin Is Actually Illegal In California, But That Could Change Soon | publisher=Business Insider | date=25 June 2014 | accessdate=26 June 2014 | author=Cosco, Joey}}</ref> After the GAO had called for increased oversight of bitcoin, the ] warned consumers of bitcoin being risky.<ref name=CFPB>{{cite news|author1=Peter Schroeder|title=CFPB warns consumers about bitcoin 'Wild West'|url=http://thehill.com/policy/finance/214831-cfpb-warns-consumers-about-bitcoin-wild-west|accessdate=27 August 2014|work=The Hill|publisher=News Communications, Inc.|date=11 August 2014}}</ref> | |||
{{as of|November 2014}}, there are no final rules at the U.S. state level yet. In March, the ] lead by superintendent ] had officially invited bitcoin exchanges to apply with them,<ref>{{cite web|title=In the Matter of Virtual Currency Exchanges|work=Public Order|url=http://www.dfs.ny.gov/about/po_vc_03112014.pdf|publisher=New York State Department of Financial Services|accessdate=30 March 2014|date=11 March 2014}}</ref> and on 17 July it published draft regulations for virtual currency businesses.<ref name=wsj72014>{{cite news|last1=Vigna|first1=Paul|title=NY Financial Regulator Releases Draft of ‘Bitlicense’ for Bitcoin Businesses|accessdate=19 July 2014|work=WSJ|publisher=Dow Jones & Company|date=17 July 2014}}</ref> Businesses would have to provide transaction receipts, disclosures about risks, policies to handle customer complaints, maintain a cybersecurity program, hire a compliance officer and verify details about their customers to follow anti-money-laundering rules, per FinCEN.<ref name=wsj72014 /> | |||
==Criminal activity== | |||
Bitcoins have been associated with online criminal behavior and ]s.<ref name="fbi_report"/> Used to obfuscate online transactions, bitcoins are seized when ] black markets are shut by authorities.<ref name="Kelion, Leo">{{cite news | url=http://www.bbc.co.uk/news/technology-26158012 | title=Five arrested in Utopia dark net marketplace crackdown | publisher=BBC | work=bbc.co.uk | date=12 February 2014 | accessdate=13 February 2014 | author=Kelion, Leo}}</ref> Criminal activities have stigmatized the currency<ref>{{cite web | url=http://www.bloomberg.com/news/2014-10-10/child-porn-seals-bitcoin-s-virtually-amoral-status-opening-line.html | title=Child Porn Seals Bitcoin’s Virtually Amoral Status: Opening Line | publisher=Bloomberg LP | work=bloomberg.com | date=Oct 10, 2014 | accessdate=9 November 2014}}</ref><ref group="note" name="illegal" /> and attracted the attention of financial regulators, legislative bodies, and law enforcement.<ref>{{cite news|url=http://www.bloomberg.com/news/2013-08-08/did-the-sec-just-validate-bitcoin-no-.html | title=The SEC Shows Why Bitcoin Is Doomed | publisher=Bloomberg LP | work=bloomberg.com | date=8 August 2013 | accessdate=20 October 2013 | author=Lavin, Tim}}</ref> ] has referred to bitcoin as a "shady online currency starting to gain legitimacy in certain parts of the world",<ref name="cnn">{{cite news|url=http://finance.fortune.cnn.com/2012/12/18/bitcoin-money-laundering/|title=Bitcoin looks primed for money laundering|publisher=CNN | work=money.cnn.com | date=18 December 2012|accessdate=18 October 2013 | author=Sanati, Cyrus}}</ref> and ] calls it "the currency of choice for seedy online activities".<ref name="washp">{{cite news | url=http://articles.washingtonpost.com/2013-10-02/business/42613812_1_digital-currency-federal-authorities-reputation | title=Authorities shut down Silk Road, the world's largest Bitcoin-based drug market|work=The Washington Post|date=2 October 2013|accessdate=21 October 2013 | author=Timothy B. Lee and Hayley Tsukayama}}</ref> The FBI stated in a 2012 report that "bitcoin will likely continue to attract cyber-criminals who view it as a means to move or steal funds".<ref name="fbi_report">{{cite web | url = http://www.wired.com/images_blogs/threatlevel/2012/05/Bitcoin-FBI.pdf | title = Bitcoins Virtual Currency: Unique Features Present Challenges for Deterring Illicit Activity | publisher = FBI | work = Cyber Intelligence Section and Criminal Intelligence Section | date = 24 April 2012 | accessdate = 2 November 2014}}</ref> Criminal activity involving bitcoin has largely centered around theft, money laundering, the use of ]s for mining, and the use of bitcoins in exchange for illegal items or services. "Like cash, it can be used for ill as well as for good."<ref name="primer" /> Certain nation states may feel that its use in circumventing ]s is also undesirable.<ref name=capcont/> Despite claims made by non-profit ] that "cryptography is the reason no one can steal bitcoins,"<ref name=foundationclaim>{{cite web | url = https://bitcoinfoundation.org/about/ | title = Developing a More Open Economy | publisher = Bitcoin Foundation | work = bitcoinfoundation.org | quote = Cryptography is the key to Bitcoin’s success. It’s the reason that no one can double spend, counterfeit or steal Bitcoins | date = 2014 | accessdate = 4 March 2014}}</ref> there have been many cases of bitcoin theft.<ref name="Economist113013Pressure" /> | |||
===Theft=== | |||
There have been many cases of bitcoin theft<ref name="Economist113013Pressure" /> despite claims made by the ] that theft is impossible.<ref name=foundationclaim /> Most large-scale thefts occur at exchanges or online wallet services that store the private keys of many users.{{fact|date=November 2014}} The thief hacks an online wallet service by finding a bug in its website or spreading malware to computers holding the private keys.<ref>{{cite news|last=Everett|first=David|title=So how can you steal Bitcoins|url=http://www.smartcard.co.uk/articles/so_how_can_you_steal_bitcoins.php|work=Smartcard & Identity News | accessdate=17 January 2014 | date=April 2012}}</ref> One way to steal bitcoins is to transfer them from the victim's bitcoin address using a stolen private key to sign the transaction.<ref>{{cite news|last=Jeffries|first=Adrianne|title=How to steal Bitcoin in three easy steps|date=19 December 2013|url=http://www.theverge.com/2013/12/19/5183356/how-to-steal-bitcoin-in-three-easy-steps|work=The Verge|accessdate=17 January 2014}}</ref> If the private key is stolen, the thief can use it to transfer all the bitcoins from the compromised address to another address of his own. In that case, the network does not have any provision to identify the thief, to block further transactions of those stolen bitcoins, or return them to the legitimate owner.<ref name=winkles/><ref name=legal1>{{cite web | author = Austin Brister | url = http://www.satoshilegal.com/articles/2014/2/16/colored-coins-can-irreversible-transfers-co-exist-with-equitable-legal-systems | title = "No Charge-Backs" Systems: Do They Invalidate Well-Established Legal Remedies? | publisher = SatoshiLegal | date = 18 October 2014 | accessdate = 14 October 2014}}</ref> | |||
Many high-profile thefts have been reported. In late November 2013, an estimated $100 million in bitcoins were stolen from the online illicit goods marketplace ], which immediately closed.<ref name=hern2013/> Users tracked the coins as they were processed and converted to cash, but no funds were recovered and no culprits identified.<ref name=hern2013>{{cite news | url=http://www.theguardian.com/technology/2013/dec/09/recovering-stolen-bitcoin-sheep-marketplace-trading-digital-currency-money | title=Recovering stolen bitcoin: a digital wild goose chase | work=The Guardian | date=9 December 2013 | first=Alex | last=Hern | accessdate=6 March 2014}}</ref> A different black market, Silk Road 2, stated that during a February 2014 hack bitcoins valued at $2.7 million were taken from escrow accounts.<ref name=silk2>{{cite news|url=http://www.bbc.co.uk/news/technology-26187725 |title=Silk Road 2 loses $2.7m in bitcoins in alleged hack |work=BBC News |date=14 February 2014 |accessdate=15 February 2014}}</ref> In late February 2014 ], one of the largest virtual currency exchanges, filed for bankruptcy in ] amid reports that 744,000 bitcoins had been stolen.<ref name="GoxBankrupt" /> Flexcoin, a bitcoin storage specialist based in ], shut down on March 2014 after saying it discovered a theft of about $650,000 in bitcoins.<ref name=ligaya2014>{{cite news | work=Financial Post | url=http://business.financialpost.com/2014/03/05/after-albertas-flexcoin-mt-gox-hacked-bitcoin-businesses-face-sting-of-free-wheeling-ways/ |title=After Alberta’s Flexcoin, Mt. Gox hacked, Bitcoin businesses face sting of free-wheeling ways | date=5 March 2014 | first=Armina | last=Ligaya | accessdate=7 March 2014}}</ref> Poloniex, a digital currency exchange, reported on March 2014 that it lost bitcoins valued at around $50,000.<ref name=truong2014>{{ cite news | url=http://www.fastcompany.com/3027373/fast-feed/another-bitcoin-exchange-another-heist | title=Another Bitcoin exchange, another heist | first=Alice | last=Truong | work=Fast Company | date=6 March 2014 | accessdate=7 March 2014 }}</ref> | |||
===Black markets=== | |||
Because of their presumed capacity to obfuscate the source of payments in online transactions and bypass money transfer controls by governments and law enforcement agencies, bitcoin have come to be used in the ] black markets.<ref name=Greenberg>{{cite news|url= http://www.forbes.com/sites/andygreenberg/2013/10/25/fbi-says-its-seized-20-million-in-bitcoins-from-ross-ulbricht-alleged-owner-of-silk-road/ |title= FBI Says It's Seized $28.5 Million In Bitcoins From Ross Ulbricht, Alleged Owner Of Silk Road |author= Andy Greenberg |publisher= Forbes.com |format= blog |date= 23 October 2013 |accessdate= 24 November 2013}}</ref> In 2012, it was estimated that 4.5% to 9% of all transactions of all bitcoin exchanges in the world were for drug trades on a single ] drugs market, ].<ref name="cmacademic">{{cite conference | url = http://www.andrew.cmu.edu/user/nicolasc/publications/Christin-WWW13.pdf | title = Traveling the Silk Road: A Measurement Analysis of a Large Anonymous Online Marketplace | publisher = Carnegie Mellon INI/CyLab | accessdate = 22 October 2013 | author = Christin, Nicolas | year = 2013 | pages = 8 | quote = we suggest to compare the estimated total volume of Silk Road transactions with the estimated total volume of transactions at all Bitcoin exchanges (including Mt.Gox, but not limited to it). The latter corresponds to the amount of money entering and leaving the Bitcoin network, and statistics for it are readily available... approximately 1,335,580 BTC were exchanged on Silk Road... approximately 29,553,384 BTC were traded in Bitcoin exchanges over the same period... The only conclusion we can draw from this comparison is that Silk Road-related trades could plausibly correspond to 4.5% to 9% of all exchange trades}}</ref> The bulk of bitcoin purchases during the time were ] in nature,<ref name="cmacademic"/> so drugs must have constituted a greater percentage of the actual goods purchased with bitcoins ] 2012. | |||
Several ] black markets where vendors sell illegal items for bitcoins have been shut by authorities. In October 2013 one such market, Silk Road, was shut down by U.S. law enforcement<ref name=Greenberg /><ref name="Kelion, Leo"/><ref>{{cite news | publisher = The Guardian | title = Bitcoin price plummets after Silk Road closure | author = Alex Hern | quote = Digital currency loses quarter of value after arrest of Ross Ulbricht, who is accused of running online drugs marketplace | date = 3 October 2013 | url = http://www.theguardian.com/technology/2013/oct/03/bitcoin-price-silk-road-ulbricht-value | accessdate = 31 October 2014}}</ref> leading to a short-term fall in the value of bitcoin.<ref>{{cite web | url = http://www.wired.com/2013/10/bitcoin-market-drops-600-million-on-silk-road-bust/ | title = Bitcoin Values Plummet $500M, Then Recover, After Silk Road Bust | author = Robert McMillan | date = 2 October 2013 | publisher = Wired | accessdate = 31 October 2014}}</ref> Alternative sites were soon available, and in early 2014 the ] reported that the closure of the Silk Road had little impact on the number of Australians selling drugs online, which had actually increased.<ref>{{cite news | url = http://www.abc.net.au/news/2014-03-31/online-drug-trade-soaring-experts-say/5354930 | publisher = ABC News | title = Silk Road closure fails to dampen illegal drug sales online, experts say | author = Katie Silver | date = 31 March 2014 | accessdate = 31 October 2014}}</ref> In early 2014, Dutch authorities closed Utopia, an online illegal goods market, and seized 900 bitcoins.<ref>{{cite web | url=http://www.independent.co.uk/life-style/gadgets-and-tech/utopia-no-more-drug-marketplace-seen-as-the-next-silk-road-shut-down-by-dutch-police-9126063.html | title=Utopia no more: Drug marketplace seen as the next Silk Road shut down by Dutch police | publisher=independent.co.uk | work=The Independent | date=13 February 2014 | accessdate=8 November 2014 | author=MURRAY-MORRIS, SOPHIE}}</ref> In late 2014, a joint police operation saw European and American authorities seize bitcoins and close 400 ] sites including the illicit goods market Silk Road 2.0.<ref>{{cite web | url=http://www.bbc.com/news/technology-29950946 | title=Huge raid to shut down 400-plus dark net sites | publisher=BBC | work=bbc.com | date=7 November 2014 | accessdate=8 November 2014 | author=Wakefield, Jane}}</ref> | |||
Several news outlets have asserted that the popularity of bitcoins hinges on the ability to use them to purchase illegal goods.<ref>{{cite news |url=http://www.economist.com/node/21563752|title=Monetarists Anonymous | publisher=The Economist Newspaper Limited|work=The Economist|date=29 September 2012| accessdate=21 October 2013}}</ref><ref>{{cite web|url=http://www.theguardian.com/world/2013/mar/22/silk-road-online-drug-marketplace|title=Silk Road: the online drug marketplace that officials seem powerless to stop|publisher=Guardian News and Media Limited|work=theguardian.com|date=22 March 2013|accessdate=20 October 2013|author=Ball, James}}</ref> Non-drug transactions were thought to be far less than the number involved in the purchase of drugs,<ref>{{cite news |url= http://www.forbes.com/sites/quora/2013/10/02/how-will-the-fbi-shut-down-of-silk-road-affect-bitcoins/|title=How Will The FBI Shut Down Of Silk Road Affect Bitcoins?|publisher=Forbes|work=Quora |date=2 October 2013|accessdate=21 October 2013|author= Mardlin, John Jeffrey}}</ref> and roughly one half of all transactions made using bitcoin ] 2013 were bets placed at a single online gambling website, ].<ref>{{cite news|url= http://arstechnica.com/business/2013/08/firm-says-online-gambling-accounts-for-almost-half-of-all-bitcoin-transactions/|title=Firm says online gambling accounts for almost half of all Bitcoin transactions |work=Ars Technica |date=24 August 2013|accessdate=21 October 2013 |author=Geuss, Megan}}</ref> One source stated online gun dealers use bitcoin to sell arms without background checks.<ref>{{cite news|url=http://www.huffingtonpost.com/2013/04/15/bitcoin-guns_n_3070828.html | title=How Bitcoin Sales Of Guns Could Undermine New Rules|publisher=TheHuffingtonPost.com, Inc. | work=huffingtonpost.com | date=15 April 2013 | accessdate=20 October 2013|author=Smith, Gerry}}</ref> The bitcoin community branded one site, Sheep Marketplace, as a scam when it prevented withdrawals and shut down after an alleged bitcoins theft.<ref name="techienews">{{cite web | url = http://www.techienews.co.uk/973470/silk-road-like-sheep-marketplace-scams-users-39k-bitcoins-worth-40-million-stolen/ | title = Silk Road-like Sheep Marketplace scams users; over 39k Bitcoins worth $40 million stolen | author = Ravi Mandalia | publisher = Techie News | date = 1 December 2013 | accessdate = 2 December 2013}}</ref> In a separate case, escrow accounts with bitcoins belonging to patrons of a different black market were hacked in early 2014.<ref name=silk2/> | |||
===Money laundering=== | |||
Bitcoins may not be ideal for money laundering because all transactions are public.<ref name="FistfulPaper201308">{{cite news | url = http://www.pcworld.com/article/2047608/bitcoin-offers-privacy-as-long-as-you-dont-cash-out-or-spend-it.html | title = Bitcoin offers privacy-as long as you don't cash out or spend it | last = Kirk | first = Jeremy | date = 28 August 2013 | work = PC World | accessdate = 31 October 2014}}</ref> Authorities have expressed concerns, however. The ]<ref name="ebawarn" /> and the FBI<ref name="fbi_report" /> have both stated that bitcoin may be used for money laundering. In early 2014, an operator of a U.S. bitcoin exchange was arrested for money laundering.<ref name=vchair>{{cite news | url=http://www.bbc.co.uk/news/technology-25919482 | title=US makes Bitcoin exchange arrests after Silk Road closure | publisher=BBC | work=bbc.co.uk | date=27 January 2014 | accessdate=28 January 2014 | author=Lee, Dave}}</ref> | |||
===Ponzi scheme=== | |||
Various journalists,<ref>{{cite web | url = http://www.slate.com/articles/news_and_politics/view_from_chicago/2013/04/bitcoin_is_a_ponzi_scheme_the_internet_currency_will_collapse.html | title = Bitcoin is a Ponzi scheme—the Internet’s favorite currency will collapse. | work = Slate | date = 11 April 2013 | accessdate = 1 April 2014 | author = Posner, Eric}}</ref> U.S. economist ],<ref>{{cite web | url = http://www.businessinsider.com/roubini-bitcoin-is-a-ponzi-scheme-and-a-conduit-for-criminal-activities-2014-3 | title = ROUBINI: 'Bitcoin Is A Ponzi Game And A Conduit For Criminal Activities' | date = 9 March 2014 | accessdate = 1 April 2014 | author = Lubin, Gus | publisher = Business Insider}}</ref><ref>{{cite web | url = http://www.cnbc.com/id/101479123 | title = Roubini launches stinging attack on bitcoin | publisher = ] | date = 10 March 2014 | accessdate = 2 July 2014 | author = Clinch, Matt}}</ref> and the head of the Estonian central bank<ref>{{cite news | url = http://www.bloomberg.com/news/2014-01-30/bitcoin-ponzi-scheme-worry-sparks-estonia-central-bank-caution.html | title = Bitcoin ‘Ponzi’ Concern Sparks Warning From Estonia Bank | publisher = Bloomberg | work = bloomberg.com | date = 31 Jan 2014 | accessdate = 1 April 2014 | author = Ott Ummelas and Milda Seputyte}}</ref> have voiced concerns that bitcoin may be a ]. Bitcoin supporters disagree.<ref name=LSP>{{cite news | url = http://libertarianstandard.com/2013/12/01/ponzi-logic-debunking-gary-north/ | title = Ponzi Logic: Debunking Gary North | last = Tucker | first = Jeffrey | date = 1 December 2013 | work = The Libertarian Standard | accessdate = 12 Feb 2014}}</ref> A 2012 report by the ] states, "it easy to assess whether or not the bitcoin system actually works like a ] or Ponzi scheme."<ref name="ECB" /> A 2014 report by the ] states: "Contrary to a widely-held opinion, bitcoin is not a deliberate Ponzi."<ref>{{cite web | title = Ponzis: The Science and Mystique of a Class of Financial Frauds | url = http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2014/07/16/000112742_20140716115536/Rendered/PDF/WPS6967.pdf | author = Kaushik Basu | publisher = ] | date = July 2014 | accessdate = 30 October 2014}}</ref> | |||
===Malware=== | |||
Bitcoin-related ] includes software that steals bitcoins from users using a variety of techniques, software that uses infected computers to mine bitcoins, and different types of ], which disable computers or prevent files from being accessed until some payment is made. Security company ] said in February 2014 that it had identified 146 types of bitcoin malware; about half of it undetectable with standard ].<ref name=haj2014/> | |||
====Unauthorized mining==== | |||
In June 2011, ] warned about the possibility that ]s could mine covertly for bitcoins.<ref>{{cite web|author=Peter Coogan |url=http://www.symantec.com/connect/blogs/bitcoin-botnet-mining |title=Bitcoin Botnet Mining|work=Symantec.com|date=17 June 2011 |accessdate = 24 January 2012|deadurl=no}}</ref> Malware used the ] capabilities of ]s built into many modern ]s.<ref>{{cite news | url = http://www.theregister.co.uk/2011/08/16/gpu_bitcoin_brute_forcing/ | title = Malware mints virtual currency using victim's GPU | work = The Register | date = 16 August 2011 | accessdate = 31 October 2014 | author = Goodin, Dan}}</ref> Although the average PC with an integrated graphics processor is virtually useless for bitcoin mining, tens of thousands of PCs laden with mining malware could produce some results.<ref name=hajb2014/> | |||
In mid-August 2011, bitcoin mining botnets were detected,<ref>{{cite web |url=http://www.infosecurity-magazine.com/view/20211/researcher-discovers-distributed-bitcoin-cracking-trojan-malware/|title=Infosecurity - Researcher discovers distributed bitcoin cracking trojan malware |publisher=Infosecurity-magazine.com|date=19 August 2011|accessdate = 24 January 2012 }}</ref> and less than three months later, bitcoin mining ] had infected ].<ref>{{cite web | url = http://www.techworld.com.au/article/405849/mac_os_x_trojan_steals_processing_power_produce_bitcoins | title = Mac OS X Trojan steals processing power to produce Bitcoins: Security researchers warn that DevilRobber malware could slow down infected Mac computers | author = Lucian Constantin | publisher = IDG communications | work = TechWorld | date = 1 November 2011 | accessdate = 24 January 2012}}</ref> | |||
In April 2013, ] organization E-Sports Entertainment was accused of hijacking 14,000 computers to mine bitcoins; the company later settled the case with the State of New Jersey.<ref>{{cite news |url= http://www.bbc.co.uk/news/technology-25014477 |title= E-Sports Entertainment settles Bitcoin botnet allegations |date= 20 November 2013 |accessdate= 24 November 2013 |work= ]}}</ref> | |||
German police arrested two people in December 2013 who customized existing botnet software to perform bitcoin mining, which police said had been used to mine at least $950,000 worth of bitcoins.<ref>{{cite news | url=http://www.coindesk.com/german-police-detain-bitcoin-hackers/ | title=German police detain ‘Bitcoin mining hackers’ | first=Nermin | last=Hajdarbegovic | date=5 December 2013 | work=CoinDesk | accessdate=7 March 2014 }}</ref> | |||
For four days in December 2013 and January 2014, Yahoo! Europe hosted an ad containing bitcoin mining malware that infected an estimated two million computers.<ref name=hajb2014>{{cite news | url=http://www.coindesk.com/yahoo-infects-2-million-european-pcs-bitcoin-malware/ | title=Yahoo infects 2 million European PCs with Bitcoin malware | first=Nermin | last=Hajdarbegovic | date=8 January 2014 | work=CoinDesk | accessdate=7 March 2014 }}</ref> The software, called ], was first detected in mid-2013 and has been bundled with many software packages. Microsoft has been removing the malware through its ] and other security software since January 2014.<ref>{{cite news | url=http://www.coindesk.com/microsoft-destroys-bitcoin-mining-botnet-sefnit/ | title=Microsoft destroys Bitcoin mining botnet Sefnit | first=Nermin | last=Hajdarbegovic | date=22 January 2014 | work=CoinDesk | accessdate=7 March 2014 }}</ref> | |||
Several reports of employees or students using university or research computers to mine bitcoins have been published.<ref>{{cite news|last1=Zagaeski|first1=Sid|title=Iowa State University Computers Hacked to Get Bitcoin Mining Power|url=https://coinreport.net/iowa-state-university-computers-hack-mine/|accessdate=13 June 2014|work=Coin Report.net|publisher=Coin Report|date=23 Apr 2014}}</ref><ref>{{cite news|last1=Hornyack|first1=Tim|title=US researcher banned for mining Bitcoin using university supercomputers|url=http://www.pcworld.com/article/2360840/us-researcher-banned-for-mining-bitcoin-using-university-supercomputers.html|accessdate=13 June 2014|work=PC world.com|publisher=IDG Consumer & SMB|date=6 June 2014}}</ref> | |||
====Malware stealing bitcoins==== | |||
Some malware can steal private keys for bitcoin wallets allowing the bitcoins themselves to be stolen. The most common type searches computers for cryptocurrency wallets to upload to a remote server where they can be cracked and their coins stolen.<ref name=haj2014/> Many of these also ] to record passwords, often avoiding the need to crack the keys.<ref name=haj2014/> A different approach detects when a bitcoin address is copied to a ] and quickly replaces it with a different address, tricking people into sending bitcoins to the wrong address.<ref name=haj2014>{{cite news | url=http://www.coindesk.com/nearly-150-strains-malware-bitcoins/ | title=Nearly 150 strains of malware are after your bitcoins | first=Nermin | last=Hajdarbegovic | date=27 February 2014 | work=CoinDesk | accessdate=7 March 2014 }}</ref> This method is effective because bitcoin transactions are irreversible. | |||
One ], spread through the Pony ], was reported in February 2014 to have stolen up to $220,000 in cryptocurrencies including 335 bitcoins from 85 wallets.<ref name=rizzo2014>{{cite news | url=http://www.coindesk.com/bitcoin-bank-flexcoin-close-600000-bitcoin-theft/ | title=Bitcoin bank Flexcoin to close after $600,000 bitcoin theft | date=4 March 2014 | first=Pete | last=Rizzo | work=CoinDesk | accessdate=7 March 2014 }}</ref> Security company ], which tracked the malware, reports that its latest version was able to steal 30 types of digital currency.<ref>{{cite news | url=http://www.reuters.com/article/2014/02/24/us-bitcoin-security-idUSBREA1N1JO20140224 | title='Pony' botnet steals bitcoins, digital currencies: Trustwave | first=Jim |last=Finkle | date=24 February 2014 | work=Reuters | accessdate=7 March 2014 }}</ref> | |||
A type Mac malware active in August 2013, Bitvanity posed as a vanity wallet address generator and stole addresses and private keys from other bitcoin client software.<ref name=southurst2014>{{cite news | url=http://www.coindesk.com/cointhief-mac-malware-steals-bitcoins/ | title=‘CoinThief’ Mac malware steals bitcoins from your wallet | first=Jon | last=Southurst | date=10 February 2014 | work=CoinDesk | accessdate=7 March 2014 }}</ref> A different trojan for Mac OS X, called CoinThief was reported in February 2014 to be responsible for multiple bitcoin thefts, including one user who lost 20 bitcoins.<ref name=southurst2014/> The software was hidden in versions of some cryptocurrency apps on ] and ].<ref name=southurst2014/> | |||
====Ransomware==== | |||
Another type of bitcoin-related malware is ]. One program called Cryptolocker, typically spread through legitimate-looking email attachments, encrypts the hard drive of an infected computer, then displays a countdown timer and demands a ransom, usually two bitcoins, to decrypt it.<ref name=guardian-ransomware>{{cite news | url=http://www.theguardian.com/technology/2014/feb/10/how-ransomware-turns-your-computer-bitcoin-miner-linkup | work=The Guardian | title=How Ransomware turns your computer into a bitcoin miner | date=10 February 2014 | accessdate=7 March 2014 }}</ref> Massachusetts police said they paid a 2 bitcoin ransom in November 2013, worth more than $1,300 at the time, to decrypt one of their hard drives.<ref>{{cite news | url=http://www.theguardian.com/technology/2013/nov/21/us-police-force-pay-bitcoin-ransom-in-cryptolocker-malware-scam | title=US police force pay bitcoin ransom in Cryptolocker malware scam | work=The Guardian | first=Samuel | last=Gibbs | date=21 November 2013 | accessdate=7 March 2014 }}</ref> Linkup, a combination ransomware and bitcoin mining program that surfaced in February 2014, disables internet access and demands credit card information to restore it, while secretly mining bitcoins.<ref name=guardian-ransomware/> | |||
==Security== | |||
Various potential attacks on the ] and its use as a payment system, real or theoretical, have been considered. The bitcoin protocol includes several features that protect it against some of those attacks, such as unauthorized spending, double spending, forging bitcoins, and tampering with the block chain.<ref name="khanbitcoin" /> Other attacks, such as theft of private keys, require due care by users. | |||
===Unauthorized spending=== | |||
When Alice sends a bitcoin to Bob, Bob becomes the new owner of the bitcoin. Eve observing the transaction might want to spend the bitcoin Bob just received, but she cannot sign the transaction without the knowledge of Bob's private key.<ref name="primer"/> | |||
===Double spending=== | |||
A specific problem that an internet payment system must solve is ], whereby a user pays the same coin to two or more different recipients. An example of such a problem would be if Eve sent a bitcoin to Alice and later sent the same bitcoin to Bob. The bitcoin network guards against double-spending by recording all bitcoin transfers in a ledger (the block chain) that is visible to all users, and ensuring for all transferred bitcoins that they haven't been previously spent.<ref name="primer"/> | |||
===Race attack=== | |||
If Eve offers to pay Alice a bitcoin in exchange for goods and signs a corresponding transaction, it is still possible that she also creates a different transaction at the same time sending the same bitcoin to Bob. By the rules, the network accepts only one of the transactions. This is called ''race attack'', since there is a race which transaction will be accepted first. Alice can reduce the risk of race attack stipulating that she will not deliver the goods until Eve's payment to Alice appears in the block chain.<ref>{{cite web | url = http://blogs.cornell.edu/info4220/2013/03/29/bitcoin-and-the-double-spending-problem/ | title = Bitcoin and the Double-spending Problem | publisher = Cornell University | date = 29 March 2013 | accessdate = 22 October 2014 | author = Erik Bonadonna}}</ref> | |||
A variant race attack (which has been called a ''Finney attack'' by reference to Hal Finney) requires the participation of a miner. Instead of sending both payment requests (to pay Bob and Alice with the same coins) to the network, Eve issues only Alice's payment request to the network, while the accomplice tries to mine a block that includes the payment to Bob instead of Alice. There is a positive probability that the rogue miner will succeed before the network, in which case the payment to Alice will be rejected. As with the plain double-spending attack, Alice can reduce the risk of a Finney attack by waiting for the payment to be included in the block chain.<ref>{{cite paper | title = Two Bitcoins at the Price of One? Double-Spending Attacks on Fast Payments in Bitcoin | url = http://eprint.iacr.org/2012/248.pdf | last1 = Karame | first1 = Ghassan O. | last2 = Androulaki | first2 = Elli | last3 = Capkun | first3 = Srdjan | publisher = International Association for Cryptologic Research | year = 2012 | accessdate = 22 October 2014}}</ref> | |||
===History modification=== | |||
The other principal way to steal bitcoins would be to modify block chain ledger entries. | |||
For example, Eve could buy something from Alice, like a sofa, by adding a signed entry to the block chain ledger equivalent to ''Eve pays Alice 100 bitcoins''. Later, after receiving the sofa, Eve could modify that block chain ledger entry to read instead: ''Eve pays Alice 1 bitcoin'', or replace Alice's address by another of Eve's addresses. Digital signatures cannot prevent this attack: Eve can simply sign her entry again after modifying it. | |||
To prevent modification attacks, each block of transactions that is added to the block chain includes a ] that is computed from the hash of the previous block as well as all the information in the block itself. When the bitcoin software notices two competing block chains, it will automatically assume that the longer one is the valid one. Therefore, in order to modify an already recorded transaction (as in the above example), the attacker would have to recalculate not just the modified block, but all the blocks after the modified one, until the modified chain is longer than the legitimate chain that the rest of the network has been building in the meantime. Consequently, for this attack to succeed, the attacker must outperform the honest part of the network.<ref name="khanbitcoin" /> | |||
Each block that is added to the block chain, starting with the block containing a given transaction, is called a ''confirmation'' of that transaction. Ideally, merchants and services that receive payment in bitcoin should wait for at least one confirmation to be distributed over the network, before assuming that the payment was done. The more confirmations that the merchant waits for, the more difficult it is for an attacker to successfully reverse the transaction in a block chain—unless the attacker controls more than half the total network power, in which case it is called a ''51% attack''.<ref name="51%">{{cite news | author1 = Michael J. Casey | author2 = Paul Vigna | title = Short-Term Fixes To Avert "51% Attack" | url = http://blogs.wsj.com/moneybeat/2014/06/16/bitbeat-a-51-attack-what-is-it-and-could-it-happen/ | accessdate = 30 June 2014 | work = Money Beat | publisher = Wall Street Journal | date = 16 June 2014}}</ref> For example, if the attacker possesses 10% of the calculation power of the bitcoin network and the shop requires 6 confirmations for a successful transaction, the probability of success of such an attack will be 0.02428%.<ref name="paper" /> | |||
<!--CLARIFY: ===== Vector76 attack ===== | |||
Also called an ''attack with confirmation'', this is a combination of the 2 aforementioned attacks which gives the perpetrator the ability to spend funds twice simply with a confirmation.{{citation needed|date=April 2014}} --> | |||
=== Selfish mining === | |||
This attack was first introduced by Ittay Eyal and Emin Gun Sirer at the beginning of November 2013.<ref>{{cite web | last1 = Eyal | first1 = Ittay | last2 = Gun Sirer | first2 = Emin | title = Majority is not Enough: Bitcoin Mining is Vulnerable | url = http://arxiv.org/abs/1311.0243 | date = 15 November 2013 | accessdate = 7 October 2014}}</ref> The attacker does not normally broadcast the blocks upon finding them. He mines his private chain and eventually (when somebody finds his own block) publishes several blocks at row. This makes the "honest" network abandon their last work and switch to the attacker's branch. As a result, honest miners lose a significant part of their revenue, whilst the attacker increases profits due to changes in relative hashpowers. | |||
According to the authors it changes the incentives for rational miners and makes them want to join the attacker's pool, increasing attacker's hashpower (which could potentially lead to ]). | |||
However, other researchers disagree with the conclusion and point out the flaws in the article.<ref>{{cite news | last = Hill | first = Kashmir | title = Bitcoin Is Not Broken | url = http://www.forbes.com/sites/kashmirhill/2013/11/06/bitcoin-is-not-broken/ | accessdate = 19 October 2014 | newspaper = Forbes | date = 6 November 2013}}</ref> | |||
==In the media== | |||
A bitcoin documentary film called ''The Rise and Rise of Bitcoin'' made its debut at the ] in New York on 23 April 2014, chronicling its origins to its explosive growth in 2013.<ref>{{cite news | url = http://newsbtc.com/2014/03/17/bitcoin-documentary-film-rise-rise-bitcoin-debut-tribeca-film-festival/ | title = Bitcoin Documentary Film ‘The Rise and Rise of Bitcoin’ To Debut at Tribeca Film Festival | date = 17 March 2014 | author = Eric Calouro | accessdate = 31 October 2014}}</ref> | |||
Several lighthearted songs celebrating Bitcoin have been released.<ref>{{cite web | url=http://blogs.wsj.com/moneybeat/2014/02/18/bitbeat-mt-goxs-pyrrhic-victory/ | title = BitBeat: Mt. Gox’s Pyrrhic Victory | publisher = The Wall Street Journal | work = Money Beat | quote='Ode to Satoshi' is a bluegrass-style song with an old-timey feel that mixes references to Satoshi Nakamoto and blockchains (and, ahem, 'the fall of old Mt. Gox') with mandolin-picking and harmonicas. | date = 18 February 2014 | accessdate = 30 September 2014 | author = Paul Vigna}}</ref><ref>{{cite web|url= http://www.coindesk.com/bitcoin-song-commemorates-bitcoin-fever/|title=Bitcoin Song Commemorates a Year of Bitcoin Fever |publisher=Coin Desk|work= |date=31 December 2013 | accessdate=22 March 2014|author=Ashton, Danny}}</ref><ref>{{cite web|url= http://bitcoinexaminer.org/7-bitcoin-songs-to-listen-to-before-2013-is-over/ | |||
| title=7 Bitcoin Songs to Listen to Before 2013 is Over |publisher=Bitcoin Examiner|work= |date=31 December 2013 | accessdate=22 March 2014|editor=Bonney, Jeremy}}</ref> Numerous U.S. comedians have made fun of "bitcoin confusion".<ref>{{cite news | title = Bitcoin confusion is comedy gold | author = Patrick Seitz | url = http://news.investors.com/technology-click/032114-694251-comedians-cannot-explain-bitcoin-but-think-it-is-funny.htm | accessdate = 5 September 2014 | work = Investors Business Daily, Tech News & Commentary | publisher = William O'Neil + Co. Incorporated | date = 21 March 2014}}</ref> In addition, a single Australian comedian has performed a stand-up comedy routine that includes bitcoin.<ref>{{cite web|url=http://bitcoinmagazine.com/9019/use-bitcoin-stand-comedy/|title=How to use Bitcoin for Stand-up Comedy |publisher=Bitcoin Magazine|work= |date=30 December 2013 | accessdate=22 March 2014|author=Connell, Michael}}</ref> | |||
In Fall 2014, undergraduate students at the ] (MIT) will receive $100 in bitcoins "to better understand this emerging technology". A student had the idea of a Bitcoin Club and raised more than half a million dollars from a MIT alum working in high-frequency trading.<ref name=MIT>{{cite news|last=Hern|first=Alex|title=MIT students to get $100 worth of bitcoin from Wall Street donor|url=http://www.theguardian.com/technology/2014/apr/29/mit-student-bitcoin-wall-street-donor|accessdate=1 May 2014|newspaper=The Guardian|date=30 April 2014}}</ref> | |||
Some U.S. political candidates, including New York City Democratic Congressional candidate ] have said they would accept campaign donations in bitcoin.<ref name="NY Congressional Candidate Jeff Kurzon is Now Taking Donations in Bitcoin">{{cite web | url = http://betabeat.com/2014/06/ny-congressional-candidate-jeff-kurzen-is-now-taking-donations-in-bitcoin | title = NY Congressional Candidate Jeff Kurzon | work = BetaBeat.com | publisher = ] | date = 3 June 2014 | accessdate = 4 June 2014 | author = Jack Smith IV}}</ref> | |||
On September 17, 2014, ] became the first comic book publisher to accept bitcoin for purchases through their DRM-Free Digital Comic Store.<ref>{{cite web | url = http://www.bleedingcool.com/2014/09/17/dynamite-to-accept-bitcoin-for-digital-comic-sales-plus-25-books-for-10/ | title = Dynamite To Accept Bitcoin For Digital Comic Sales Plus 25 Books For $10 | date = 17 September 2014 | author = Dan Wickline | publisher = bleedingcool.com | accessdate = 2 November 2014}}</ref>{{third-party-inline|date=October 2014}} | |||
==See also== | ==See also== | ||
{{Div col}} | |||
* ] | * ] | ||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
* ] | |||
{{Div col end}} | |||
{{Portal bar|Cryptography|Economics|Free software|Internet|Numismatics}} | |||
==Notes== | ==Notes== | ||
{{Notelist}} | |||
{{Reflist|group=note|30em}} | |||
==References== | ==References== | ||
{{Reflist |
{{Reflist}} | ||
== |
==Further reading== | ||
*{{cite web|last=Nakamoto|first=Satoshi|date=31 October 2008|title=Bitcoin: A Peer-to-Peer Electronic Cash System|url=https://bitcoin.org/bitcoin.pdf|url-status=dead|archive-url=https://web.archive.org/web/20140320135003/https://bitcoin.org/bitcoin.pdf|archive-date=20 March 2014|access-date=28 April 2014|publisher=bitcoin.org}} | |||
{{Commons category|Bitcoin}} | |||
{{Wiktionary}} | {{Wiktionary}} | ||
{{Wikibooks|Professionalism|BitTorrent and BitCoin}} | |||
{{Wikibooks|Strategy for Information Markets|Micropayments}} | |||
* - unofficial website managed by Bitcoin core developers. | |||
* {{Dmoz|Science/Social_Sciences/Economics/Financial_Economics/Currency_and_Money/Alternative_Monetary_Systems/Bitcoin}} | |||
* at ] | |||
* Bitcoin, Instituto Nacional de Tecnologías de la Communicación (INTECO), Spain, or National Institute of Communication Technologies (undated, 47pp, in English). | |||
* | |||
* ] - - historical statistics in time series downloadable format. | |||
{{Bitcoin}} | {{Bitcoin}} | ||
{{Cryptocurrencies}} | {{Cryptocurrencies}} | ||
{{Currency symbols}} | |||
{{Authority control}} | |||
{{Subject bar|commons=Bitcoin|portal1=Business and economics|portal2=Free and open-source software|portal3=Internet|portal4=Numismatics|portal5=Money}} | |||
] | ] | ||
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Latest revision as of 02:21, 11 January 2025
Decentralized digital currency For the colloquial expression for coinage, see Bit (money). "₿" redirects here. Not to be confused with "฿" for Thai baht.
Official logo from bitcoin.org | |
Denominations | |
---|---|
Plural | Bitcoins |
Symbol | ₿ (Unicode: U+20BF ₿ BITCOIN SIGN) |
Code | BTC |
Precision | 10 |
Subunits | |
1⁄1000 | Millibitcoin |
1⁄1000000 | Microbitcoin |
1⁄100000000 | Satoshi |
Development | |
Original author(s) | Satoshi Nakamoto |
White paper | "Bitcoin: A Peer-to-Peer Electronic Cash System" |
Implementation(s) | Bitcoin Core |
Initial release | 0.1.0 / 9 January 2009 (16 years ago) (2009-01-09) |
Latest release | 28.0 / 4 October 2024 (3 months ago) (2024-10-04) |
Code repository | github |
Development status | Active |
Written in | C++ |
Source model | Free and open-source software |
License | MIT License |
Ledger | |
Ledger start | 3 January 2009 (16 years ago) (2009-01-03) |
Timestamping scheme | Proof of work (partial hash inversion) |
Hash function | SHA-256 (two rounds) |
Issuance schedule | Decentralized (block reward) Initially ₿50 per block, halved every 210,000 blocks |
Block reward | ₿3.125 (as of 2024) |
Block time | 10 minutes |
Circulating supply | ₿19,591,231 (as of 6 January 2024) |
Supply limit | ₿21,000,000 |
Valuation | |
Exchange rate | Floating |
Demographics | |
Official user(s) | El Salvador |
Website | |
Website | bitcoin |
Bitcoin (abbreviation: BTC; sign: ₿) is the first decentralized cryptocurrency. Based on a free-market ideology, bitcoin was invented in 2008 by Satoshi Nakamoto, an unknown person. Use of bitcoin as a currency began in 2009, with the release of its open-source implementation. In 2021, El Salvador adopted it as legal tender. It is mostly seen as an investment and has been described by some scholars as an economic bubble. As bitcoin is pseudonymous, its use by criminals has attracted the attention of regulators, leading to its ban by several countries as of 2021.
Nodes in the peer-to-peer bitcoin network verify transactions through cryptography and record them in a public distributed ledger, called a blockchain, without central oversight. Consensus between nodes is achieved using a computationally intensive process based on proof of work, called mining, that secures the bitcoin blockchain. Mining consumes large quantities of electricity and has been criticized for its environmental impact.
History
Main article: History of bitcoinBackground
Before bitcoin, several digital cash technologies were released, starting with David Chaum's ecash in the 1980s. The idea that solutions to computational puzzles could have some value was first proposed by cryptographers Cynthia Dwork and Moni Naor in 1992. The concept was independently rediscovered by Adam Back who developed Hashcash, a proof-of-work scheme for spam control in 1997. The first proposals for distributed digital scarcity-based cryptocurrencies came from cypherpunks Wei Dai (b-money) and Nick Szabo (bit gold) in 1998. In 2004, Hal Finney developed the first currency based on reusable proof of work. These various attempts were not successful: Chaum's concept required centralized control and no banks wanted to sign on, Hashcash had no protection against double-spending, while b-money and bit gold were not resistant to Sybil attacks.
2008–2009: Creation
External image | |
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Cover page of The Times 3 January 2009 showing the headline used in the genesis block |
The domain name bitcoin.org was registered on 18 August 2008. On 31 October 2008, a link to a white paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System was posted to a cryptography mailing list. Nakamoto implemented the bitcoin software as open-source code and released it in January 2009. Nakamoto's identity remains unknown. According to computer scientist Arvind Narayanan, all individual components of bitcoin originated in earlier academic literature. Nakamoto's innovation was their complex interplay resulting in the first decentralized, Sybil resistant, Byzantine fault tolerant digital cash system, that would eventually be referred to as the first blockchain. Nakamoto's paper was not peer reviewed and was initially ignored by academics, who argued that it could not work.
On 3 January 2009, the bitcoin network was created when Nakamoto mined the starting block of the chain, known as the genesis block. Embedded in this block was the text "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks", which is the date and headline of an issue of The Times newspaper. Nine days later, Hal Finney received the first bitcoin transaction: ten bitcoins from Nakamoto. Wei Dai and Nick Szabo were also early supporters. On May 22, 2010, the first known commercial transaction using bitcoin occurred when programmer Laszlo Hanyecz bought two Papa John's pizzas for ₿10,000, in what would later be celebrated as "Bitcoin Pizza Day".
2010–2012: Early growth
Blockchain analysts estimate that Nakamoto had mined about one million bitcoins before disappearing in 2010 when he handed the network alert key and control of the code repository over to Gavin Andresen. Andresen later became lead developer at the Bitcoin Foundation, an organization founded in September 2012 to promote bitcoin.
After early "proof-of-concept" transactions, the first major users of bitcoin were black markets, such as the dark web Silk Road. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9 million, worth about $214 million.
2013–2014: First regulatory actions
In March 2013, the US Financial Crimes Enforcement Network (FinCEN) established regulatory guidelines for "decentralized virtual currencies" such as bitcoin, classifying American bitcoin miners who sell their generated bitcoins as money services businesses, subject to registration and other legal obligations. In May 2013, US authorities seized the unregistered exchange Mt. Gox. In June 2013, the US Drug Enforcement Administration seized ₿11.02 from a man attempting to use them to buy illegal substances. This marked the first time a government agency had seized bitcoins. The FBI seized about ₿30,000 in October 2013 from Silk Road, following the arrest of its founder Ross Ulbricht.
In December 2013, the People's Bank of China prohibited Chinese financial institutions from using bitcoin. After the announcement, the value of bitcoin dropped, and Baidu no longer accepted bitcoins for certain services. Buying real-world goods with any virtual currency had been illegal in China since at least 2009.
2015–2019
Research produced by the University of Cambridge estimated that in 2017, there were 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin. In August 2017, the SegWit software upgrade was activated. Segwit was intended to support the Lightning Network as well as improve scalability. SegWit opponents, who supported larger blocks as a scalability solution, forked to create Bitcoin Cash, one of many forks of bitcoin.
In December 2017, the first futures on bitcoin was introduced by the Chicago Mercantile Exchange (CME).
In February 2018, the price crashed after China imposed a complete ban on bitcoin trading. The percentage of bitcoin trading in the Chinese renminbi fell from over 90% in September 2017 to less than 1% in June 2018. During the same year, bitcoin prices were negatively affected by several hacks or thefts from cryptocurrency exchanges.
2020–present
In 2020, some major companies and institutions started to acquire bitcoin: MicroStrategy invested $250 million in bitcoin as a treasury reserve asset, Square, Inc., $50 million, and MassMutual, $100 million. In November 2020, PayPal added support for bitcoin in the US.
In February 2021, bitcoin's market capitalization reached $1 trillion for the first time. In November 2021, the Taproot soft-fork upgrade was activated, adding support for Schnorr signatures, improved functionality of smart contracts and Lightning Network. Before, bitcoin only used a custom elliptic curve with the ECDSA algorithm to produce signatures. In September 2021, bitcoin became legal tender in El Salvador, alongside the US dollar. In October 2021, the first bitcoin futures exchange-traded fund (ETF), called BITO, from ProShares was approved by the SEC and listed on the CME.
In May and June 2022, the bitcoin price fell following the collapses of TerraUSD, a stablecoin, and the Celsius Network, a cryptocurrency loan company.
In 2023, ordinals—non-fungible tokens (NFTs)—on bitcoin, went live. As of June 2023, River Financial estimated that bitcoin had 81.7 million users, about 1% of the global population. In January 2024, the first 11 US spot bitcoin ETFs began trading, offering direct exposure to bitcoin for the first time on American stock exchanges. In December 2024, bitcoin price reached $100,000 for the first time, as US president-elect Donald Trump promised to make the US the "crypto capital of the planet" and to stockpile bitcoin. The same month, BlackRock, the world's largest asset manager, recommended investors to allocate up to 2% of their portfolio to bitcoin.
Design
Main article: Bitcoin protocolUnits and divisibility
The unit of account of the bitcoin system is the bitcoin. It is most commonly represented with the symbol ₿ and the currency code BTC. However, the BTC code does not conform to ISO 4217 as BT is the country code of Bhutan, and ISO 4217 requires the first letter used in global commodities to be 'X'. XBT, a code that conforms to ISO 4217 though not officially part of it, is used by Bloomberg L.P.
No uniform capitalization convention exists; some sources use Bitcoin, capitalized, to refer to the technology and network, and bitcoin, lowercase, for the unit of account. The Cambridge Advanced Learner's Dictionary and the Oxford Advanced Learner's Dictionary use the capitalized and lowercase variants without distinction.
One bitcoin is divisible to eight decimal places. Units for smaller amounts of bitcoin are the millibitcoin (mBTC), equal to 1⁄1000 bitcoin, and the satoshi (sat), representing 1⁄100000000 (one hundred millionth) bitcoin, the smallest amount possible. 100,000 satoshis are one mBTC.
Blockchain
Further information: Blockchain § Structure and designAs a decentralized system, bitcoin operates without a central authority or single administrator, so that anyone can create a new bitcoin address and transact without needing any approval. This is accomplished through a specialized distributed ledger called a blockchain that records bitcoin transactions.
The blockchain is implemented as an ordered list of blocks. Each block contains a SHA-256 hash of the previous block, chaining them in chronological order. The blockchain is maintained by a peer-to-peer network. Individual blocks, public addresses, and transactions within blocks are public information, and can be examined using a blockchain explorer.
Nodes validate and broadcast transactions, each maintaining a copy of the blockchain for ownership verification. A new block is created every 10 minutes on average, updating the blockchain across all nodes without central oversight. This process tracks bitcoin spending, ensuring each bitcoin is spent only once. Unlike a traditional ledger that tracks physical currency, bitcoins exist digitally as unspent outputs of transactions.
Addresses and transactions
In the blockchain, bitcoins are linked to specific addresses that are hashes of a public key. Creating an address involves generating a random private key and then computing the corresponding address. This process is almost instant, but the reverse (finding the private key for a given address) is nearly impossible. Publishing a bitcoin address does not risk its private key, and it is extremely unlikely to accidentally generate a used key with funds. To use bitcoins, owners need their private key to digitally sign transactions, which are verified by the network using the public key, keeping the private key secret.
Bitcoin transactions use a Forth-like scripting language, involving one or more inputs and outputs. When sending bitcoins, a user specifies the recipients' addresses and the amount for each output. This allows sending bitcoins to several recipients in a single transaction. To prevent double-spending, each input must refer to a previous unspent output in the blockchain. Using multiple inputs is similar to using multiple coins in a cash transaction. As in a cash transaction, the sum of inputs can exceed the intended sum of payments. In such a case, an additional output can return the change back to the payer. Unallocated input satoshis in the transaction become the transaction fee.
Losing a private key means losing access to the bitcoins, with no other proof of ownership accepted by the protocol. For instance, in 2013, a user lost ₿7,500, valued at US$7.5 million, by accidentally discarding a hard drive with the private key. It is estimated that around 20% of all bitcoins are lost. The private key must also be kept secret as its exposure, such as through a data breach, can lead to theft of the associated bitcoins. As of December 2017, approximately ₿980,000 had been stolen from cryptocurrency exchanges.
Mining
See also: Bitcoin protocol § MiningThe mining process in bitcoin involves maintaining the blockchain through computer processing power. Miners group and broadcast new transactions into blocks, which are then verified by the network. Each block must contain a proof of work (PoW) to be accepted, involving finding a nonce number that, combined with the block content, produces a hash numerically smaller than the network's difficulty target. This PoW is simple to verify but hard to generate, requiring many attempts. PoW forms the basis of bitcoin's consensus mechanism.
The difficulty of generating a block is deterministically adjusted based on the mining power on the network by changing the difficulty target, which is recalibrated every 2,016 blocks (approximately two weeks) to maintain an average time of ten minutes between new blocks. The process requires significant computational power and specialized hardware.
Miners who successfully find a new block can collect transaction fees from the included transactions and a set reward in bitcoins. To claim this reward, a special transaction called a coinbase is included in the block, with the miner as the payee. All bitcoins in existence have been created through this type of transaction. This reward is halved every 210,000 blocks until ₿21 million, with new bitcoin issuance slated to end around 2140. Afterward, miners will only earn from transaction fees. These fees are determined by the transaction's size and the amount of data stored, measured in satoshis per byte.
The proof of work system and the chaining of blocks make blockchain modifications very difficult, as altering one block requires changing all subsequent blocks. As more blocks are added, modifying older blocks becomes increasingly challenging. In case of disagreement, nodes trust the longest chain, which required the greatest amount of effort to produce. To tamper or censor the ledger, one needs to control the majority of the global hashrate. The high cost required to reach this level of computational power secures the bitcoin blockchain.
Bitcoin mining's environmental impact is controversial and has attracted the attention of regulators, leading to restrictions or incentives in various jurisdictions. As of 2022, a non-peer-reviewed study by the Cambridge Centre for Alternative Finance (CCAF) estimated that bitcoin mining represented 0.4% of global electricity consumption. Another 2022 non-peer-reviewed commentary published in Joule estimated that bitcoin mining was responsible for 0.2% of world greenhouse gas emissions. About half of the electricity used is generated through fossil fuels. Moreover, mining hardware's short lifespan results in electronic waste. The amount of electrical energy consumed, and the e-waste generated, is comparable to that of Greece and the Netherlands, respectively.
Privacy and fungibility
Bitcoin is pseudonymous, with funds linked to addresses, not real-world identities. While the owners of these addresses are not directly identified, all transactions are public on the blockchain. Patterns of use, like spending coins from multiple inputs, can hint at a common owner. Public data can sometimes be matched with known address owners. Bitcoin exchanges might also need to collect personal data as per legal requirements. For enhanced privacy, users can generate a new address for each transaction.
In the bitcoin network, each bitcoin is treated equally, ensuring basic fungibility. However, users and applications can choose to differentiate between bitcoins. While wallets and software treat all bitcoins the same, each bitcoin's transaction history is recorded on the blockchain. This public record allows for chain analysis, where users can identify and potentially reject bitcoins from controversial sources. For example, in 2012, Mt. Gox froze accounts containing bitcoins identified as stolen.
Wallets
For broader coverage of this topic, see Cryptocurrency wallet. Screenshot of Bitcoin CoreA paper wallet with the address as a QR code while the private key is hiddenA hardware wallet which processes bitcoin transactions without exposing private keysBitcoin wallets were the first cryptocurrency wallets, enabling users to store the information necessary to transact bitcoins. The first wallet program, simply named Bitcoin, and sometimes referred to as the Satoshi client, was released in 2009 by Nakamoto as open-source software. Bitcoin Core is among the best known clients. Forks of Bitcoin Core exist such as Bitcoin Unlimited. Wallets can be full clients, with a full copy of the blockchain to check the validity of mined blocks, or lightweight clients, just to send and receive transactions without a local copy of the entire blockchain. Third-party internet services called online wallets store users' credentials on their servers, making them susceptible of hacks. Cold storage protects bitcoins from such hacks by keeping private keys offline, either through specialized hardware wallets or paper printouts.
Scalability and decentralization challenges
Nakamoto limited the block size to one megabyte. The limited block size and frequency can lead to delayed processing of transactions, increased fees and a bitcoin scalability problem. The Lightning Network, second-layer routing network, is a potential scaling solution.
Research shows a trend towards centralization in bitcoin as miners join pools for stable income. If a single miner or pool controls more than 50% of the hashing power, it would allow them to censor transactions and double-spend coins. In 2014, mining pool Ghash.io reached 51% mining power, causing safety concerns, but later voluntarily capped its power at 39.99% for the benefit of the whole network. A few entities also dominate other parts of the ecosystem such as the client software, online wallets, and simplified payment verification (SPV) clients.
Economics and usage
Main article: Economics of bitcoinBitcoin's theoretical roots and ideology
According to the European Central Bank, the decentralization of money offered by bitcoin has its theoretical roots in the Austrian school of economics, especially with Friedrich Hayek's The Denationalisation of Money, in which he advocates a complete free market in the production, distribution and management of money to end the monopoly of central banks. Sociologist Nigel Dodd argues that the essence of the bitcoin ideology is to remove money from social, as well as governmental, control. The Economist describes bitcoin as "a techno-anarchist project to create an online version of cash, a way for people to transact without the possibility of interference from malicious governments or banks". These philosophical ideas initially attracted libertarians and anarchists. Economist Paul Krugman argues that cryptocurrencies like bitcoin are only used by bank skeptics and criminals.
Recognition as a currency and legal status
Money serves three purposes: a store of value, a medium of exchange, and a unit of account. According to The Economist in 2014, bitcoin functions best as a medium of exchange. In 2015, The Economist noted that bitcoins had three qualities useful in a currency: they are "hard to earn, limited in supply and easy to verify". However, a 2018 assessment by The Economist stated that cryptocurrencies met none of these three criteria. Per some researchers, as of 2015, bitcoin functions more as a payment system than as a currency. In 2014, economist Robert J. Shiller wrote that bitcoin has potential as a unit of account for measuring the relative value of goods, as with Chile's Unidad de Fomento, but that "Bitcoin in its present form... doesn't really solve any sensible economic problem". François R. Velde, Senior Economist at the Chicago Fed, described bitcoin as "an elegant solution to the problem of creating a digital currency". David Andolfatto, Vice President at the Federal Reserve Bank of St. Louis, stated that bitcoin is a threat to the establishment, which he argues is a good thing for the Federal Reserve System and other central banks, because it prompts these institutions to operate sound policies.
The legal status of bitcoin varies substantially from one jurisdiction to another. Because of its decentralized nature and its global presence, regulating bitcoin is difficult. However, the use of bitcoin can be criminalized, and shutting down exchanges and the peer-to-peer economy in a given country would constitute a de facto ban. The use of bitcoin by criminals has attracted the attention of financial regulators, legislative bodies, and law enforcement. Nobel-prize winning economist Joseph Stiglitz says that bitcoin's anonymity encourages money laundering and other crimes. This is the main justification behind bitcoin bans. As of November 2021, nine countries applied an absolute ban (Algeria, Bangladesh, China, Egypt, Iraq, Morocco, Nepal, Qatar, and Tunisia) while another 42 countries had an implicit ban. Bitcoin is only legal tender in El Salvador.
Use for payments
As of 2018, bitcoin is rarely used in transactions with merchants, but it is popular to purchase illegal goods online. Prices are not usually quoted in bitcoin and trades involve conversions into fiat currencies. Commonly cited reasons for not using bitcoin include high costs, the inability to process chargebacks, high price volatility, long transaction times, and transaction fees (especially for small purchases). Bloomberg reported that bitcoin was being used for large-item purchases on the site Overstock.com and for cross-border payments to freelancers. As of 2015, there was little sign of bitcoin use in international remittances despite high fees charged by banks and Western Union who compete in this market. Despite associated risks and costs, in 2022, a growing use of bitcoin, alongside cash and cards, was reported in restaurant business.
In September 2021, the Bitcoin Law made bitcoin legal tender in El Salvador, alongside the US dollar. The adoption has been criticized internationally and within El Salvador. In 2022, the International Monetary Fund (IMF) urged El Salvador to reverse its decision. As of 2022, the use of Bitcoin in El Salvador remains low: 80% of businesses refused to accept it. In April 2022, the Central African Republic (CAR) adopted bitcoin as legal tender alongside the CFA franc, but repealed the reform one year later.
Bitcoin is also used by some governments. For instance, the Iranian government initially opposed cryptocurrencies, but later saw them as an opportunity to circumvent sanctions. Since 2020, Iran has required local bitcoin miners to sell bitcoin to the Central Bank of Iran, allowing the central bank to use it for imports. Some constituent states also accept tax payments in bitcoin, including Colorado (US) and Zug (Switzerland). As of 2023, the US government owned more than $5 billion worth of seized bitcoin.
Use for investment and status as an economic bubble
Further information: Cryptocurrency bubbleAs of 2018, the overwhelming majority of bitcoin transactions took place on cryptocurrency exchanges. Since 2014, regulated bitcoin funds also allow exposure to the asset or to futures as an investment. Bitcoin is used as a store of value: individuals and companies such as the Winklevoss twins and Elon Musk's companies SpaceX and Tesla have massively invested in bitcoin. Bitcoin wealth is highly concentrated, with 0.01% holding 27% of in-circulation currency, as of 2021. As of September 2023, El Salvador had $76.5 million worth of bitcoin in its international reserves.
In 2018, research published in the Journal of Monetary Economics concluded that price manipulation occurred during the Mt. Gox bitcoin theft and that the market remained vulnerable to manipulation. Research published in The Journal of Finance also suggested that trading associated with increases in the amount of the Tether cryptocurrency and associated trading at the Bitfinex exchange accounted for about half of the price increase in bitcoin in late 2017.
Bitcoin, along with other cryptocurrencies, has been described as an economic bubble by several economists, including Nobel Prize in Economics laureates, such as Joseph Stiglitz, James Heckman, and Paul Krugman. Another recipient of the prize, Robert Shiller, argues that bitcoin is rather a fad that may become an asset class. He describes its price growth as an "epidemic", driven by contagious narratives. In 2024, Jean Tirole, also Nobel laureate, described bitcoin as a "pure bubble" as its intrinsic value is zero. According to him, some bubbles are long-lasting such as gold and fiat currencies, and it's impossible to predict whether bitcoin will collapse like other financial bubbles or become the new gold. The same year, Federal Reserve Chair Jerome Powell described bitcoin as a digital competitor to gold but not to the dollar as he argued it is a highly volatile speculative asset not used as a form of payment.
According to research published in the International Review of Financial Analysis in 2018, bitcoin as an asset is highly volatile and does not behave like any other conventional asset. According to one 2022 analysis published in The Journal of Alternative Investments, bitcoin was less volatile than oil, silver, US Treasuries, and 190 stocks in the S&P 500 during and after the 2020 stock market crash. The term hodl was created in December 2013 for holding bitcoin rather than selling it during periods of volatility.
Other economists, investors, and the central bank of Estonia have described bitcoin as a potential Ponzi scheme. Legal scholar Eric Posner disagrees, however, as "a real Ponzi scheme takes fraud; bitcoin, by contrast, seems more like a collective delusion". A 2014 World Bank report also concluded that bitcoin was not a deliberate Ponzi scheme.
See also
Notes
- ^ Named after Satoshi Nakamoto
- ^ The exact number is ₿20,999,999.9769.
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It doesn't serve any socially useful function.
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"People use bitcoin as a speculative asset. It's like gold, it's just like gold, only it's virtual, it's digital. People are not using it as a form of payment or a store of value," he said. "It's highly volatile. It's not a competitor for the dollar; it's really a competitor for gold."
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Further reading
- Nakamoto, Satoshi (31 October 2008). "Bitcoin: A Peer-to-Peer Electronic Cash System" (PDF). bitcoin.org. Archived from the original (PDF) on 20 March 2014. Retrieved 28 April 2014.
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