Bitcoin
| Bitcoin | |
|---|---|
| |
| Commonly used logo of bitcoin | |
| Denominations | |
| Plural | Bitcoins |
| Symbol | ₿ (Unicode: U+20BF ₿ BITCOIN SIGN) |
| Code | BTC |
| Precision | 10⁻⁸ |
| Subunits |
59 Markets.com, “Crypto market analysis: What are the features of cryptocurrency?” Archived. Retrieved October 2025 |
| Development | |
| Original author | Satoshi Nakamoto |
| White paper | Bitcoin: A Peer-to-Peer Electronic Cash System |
| Implementation | Bitcoin Core |
| Initial release | 0.1.0 / 9 January 2009 (16 years ago) |
| Latest release | 30.0.0 / 11 October 2025 (34 days ago) |
| Code repository | GitHub |
| Development status | Active |
| Written in | C++ |
| Source model | Free and Open Source Software |
| License | MIT Licence |
| Ledger | |
| Ledger start | 3 January 2009 (16 years ago) |
| Timestamping scheme | Proof of work (partial hash inversion) |
| Hash function | SHA-256 (two rounds) |
| Issuance | Decentralized (block reward), Initially ₿50 per block, halved every 210,000 blocks |
| Block reward | ₿3.125 (as of 2025) |
| Block time | 10 minutes |
| Circulating supply | ₿19,934,271 (as of 14 October 2025) |
| Supply limit | ₿21,000,000 |
| Valuation | |
| Exchange rate | Floating |
| Website | bitcoin.org |
Template:Infobox cryptocurrency
Bitcoin (abbreviated BTC; symbol: ₿) is a decentralized digital asset and the first widely adopted cryptocurrency. It was introduced in 2008 when an individual or group working under the pseudonym Satoshi Nakamoto published a white paper outlining a peer-to-peer system for electronic transactions without the need for a central authority.<ref name="whoissn">Template:Cite news</ref>
Bitcoin’s software implementation was released as open-source in early 2009,<ref name="NY2011">Template:Cite magazine</ref> enabling the first transactions on its distributed ledger, known as the blockchain. The protocol uses public-key cryptography to verify ownership and a proof-of-work mechanism—commonly associated with mining—to secure the network and achieve consensus between participating computers.<ref name="Antonopoulos2014">Template:Cite book</ref>Template:Rp
Bitcoin gained international recognition during the 2010s and early 2020s, eventually becoming legal tender in El Salvador between 2021 and 2025—the first instance of nationwide adoption of a cryptocurrency as official currency.<ref name="FTlegal">Template:Cite news</ref>
Although Bitcoin allows users to transact pseudonymously, its association with criminal activity and market volatility has contributed to restrictions and prohibitions in several countries.<ref name="SunYin2019">Template:Cite journal</ref>
Despite regulatory uncertainty, Bitcoin remains the most widely recognized and valuable digital currency, supported by a global network of nodes, exchanges, wallet providers, and payment services.
History
Background
Before Bitcoin’s introduction in 2009, multiple attempts had been made to design digital forms of money that could function without conventional financial intermediaries. Early work in this field can be traced to the 1980s with David Chaum’s ecash, which relied on a centralized server for issuing and validating cryptographic tokens.<ref name="Narayanan2017">Template:Cite journal</ref>
In the 1990s, the idea that computational puzzles could provide economic value inspired further work. Cryptographers Cynthia Dwork and Moni Naor proposed the use of proof-of-work functions in 1992 as a means of combating email spam by forcing senders to expend computational effort.<ref>Template:Cite journal</ref><ref name="Narayanan2017" />
The concept resurfaced in 1997 when Adam Back introduced Hashcash, a proof-of-work scheme designed to deter bulk email attacks.<ref name="Narayanan2017" /> Although Hashcash was not intended as a digital currency, its mechanism became a foundational element of Bitcoin’s design.
Inspired by the cypherpunk movement, several proposals for decentralized digital money emerged in 1998. Wei Dai’s b-money and Nick Szabo’s bit gold each outlined systems for creating scarce digital assets without trusted third parties, though neither achieved practical deployment.<ref>Template:Cite journal</ref>
In 2004, developer Hal Finney built the first reusable proof-of-work system, which introduced features resembling later cryptocurrencies.<ref>Template:Cite book</ref>
Despite these advancements, pre-Bitcoin systems suffered from limitations such as centralization, vulnerability to double-spending, or susceptibility to Sybil attacks.<ref name="Narayanan2017" />
Creation
Bitcoin was formally introduced on 31 October 2008, when a white paper titled Bitcoin: A Peer-to-Peer Electronic Cash System was posted to the Cryptography Mailing List by a user identifying as Satoshi Nakamoto. The document proposed a decentralized network in which participants could collectively maintain a public ledger using proof-of-work to validate transactions.<ref name="whoissn" />
The first version of the Bitcoin software (v0.1) was released in January 2009.<ref name="Antonopoulos2014" />Template:Rp Nakamoto mined the “genesis block,” marking the start of the blockchain on 3 January 2009. Embedded in this first block was a headline from The Times newspaper referencing the ongoing financial crisis, interpreted by many as a commentary on the fragility of centralized banking.<ref>Template:Cite news</ref>
The first publicly verified Bitcoin transaction occurred when Hal Finney received 10 BTC from Nakamoto on 12 January 2009.<ref>Template:Cite web</ref> Nakamoto continued to collaborate with early developers until 2010, after which their involvement gradually diminished before ceasing entirely. Nakamoto’s identity remains unknown.
Early development
During its first years, Bitcoin attracted attention among cryptography hobbyists and online communities. In 2010, the first notable commercial transaction was recorded when a programmer famously purchased two pizzas for 10,000 BTC, an event now commemorated annually as “Bitcoin Pizza Day.”<ref>Template:Cite web</ref>
The establishment of cryptocurrency exchanges beginning in 2010 enabled wider participation, making it possible to convert bitcoins into government-issued currencies. Early volatility was common, and security breaches at several exchanges brought further scrutiny.<ref>Template:Cite news</ref>
Growing mainstream attention
By the mid-2010s, Bitcoin had gained global recognition. Media coverage, corporate interest, and the emergence of derivative markets contributed to rising adoption. At the same time, regulators began issuing warnings about the risks associated with cryptocurrency trading, including fraud, price manipulation, and security vulnerabilities.<ref>Template:Cite journal</ref>