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 |
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Bitcoin (abbreviation: BTC; sign: ₿) is a digital form of money without any physical existence. Unlike traditional currencies, it operates without central control or banks. Transactions occur over a decentralized network of thousands of interconnected computers, known as nodes.¹
Based on early concepts of digital money, the origins of cryptocurrency trace back to 1983, when David Chaum introduced eCash and launched Digicash in 1989. In 2008, Satoshi Nakamoto published [[Bitcoin: A Peer-to-Peer Electronic Cash System]], introducing blockchain technology and decentralization.² Bitcoin’s network launched in 2009 with the mining of the Genesis block.
Key milestones include the first real transaction on May 22 2010, surpassing $1 in 2011, and recognition by 2013. From 2021 to 2025, Bitcoin achieved global legitimacy through SEC‑approved ETFs, PayPal integration, and U.S. regulatory frameworks under President Donald Trump.³
Bitcoin transactions occur on a decentralized blockchain network where users transfer digital currency between wallets. Verified by miners using cryptography and proof‑of‑work, each transaction ensures transparency and security, enabling peer‑to‑peer payments without intermediaries.⁴
History
Bitcoin, often called digital gold, has transformed from a concept into a global financial revolution.⁵ Tracing Bitcoin’s evolution reveals more than just technological progress—it reflects society’s changing view of money, trust, and value.
Background
Projects like DigiCash, Hashcash, Bit gold, and b‑money pioneered ideas of digital scarcity, privacy, and proof‑of‑work.⁶ David Chaum’s DigiCash introduced anonymous transactions but failed commercially.⁷ Wei Dai proposed b‑money; Adam Back’s Hashcash fought spam with PoW.⁸ Douglas Jackson’s E‑gold (1996) and Nick Szabo’s Bit Gold (1998) shaped the idea of scarce, decentralized money.⁹ In 2004, Hal Finney’s Reusable Proof of Work (RPOW) completed the groundwork for Bitcoin.
2008–2009: Creation
Bitcoin was conceptualized after the 2008 financial crisis as an independent digital money system.¹⁰ Early adopters were cypherpunks and libertarians. No market value existed initially; coins were exchanged experimentally.¹¹
2010–2012: Early growth
In May 2010, Laszlo Hanyecz paid 10 000 BTC for two pizzas — the first real transaction. Bitcoin surpassed $1 in 2011 and closed 2011 at $5.20. The first halving in Nov 2012 reduced rewards from 50 → 25 BTC.¹³
2013–2014: Regulatory actions
Bitcoin’s market cap passed $1 billion in March 2013; the first ATM appeared in Canada. By Nov 2013 it hit $1 000 on Mt. Gox.¹⁶ In 2014 the exchange collapsed after a hack, spurring debate over security and regulation.¹⁴
2015–2020: Global adoption
Microsoft accepted BTC in 2015; Japan legalized crypto in 2016.¹⁹ CME Group launched the Bitcoin Reference Rate and futures in 2017, when prices peaked at $19 188.²⁰ COVID‑19 fears in 2020 sparked a new rally.
2021–2023: Institutional Adoption
Bitcoin hit $64 895 (Apr 2021) and $69 000 (Nov 2021). Companies like Tesla and MicroStrategy held BTC on balance sheets.²¹ PayPal enabled crypto payments and ProShares launched the first U.S. Bitcoin ETF.²² The collapse of FTX in 2022 led to a market downturn, with prices recovering to $42 258 by Dec 2023.²³
2024–2025: Mainstream Finance
The SEC approved spot Bitcoin ETFs in Jan 2024, broadening institutional access.²⁴ In 2025, the GENIUS Act established crypto standards and a U.S. Bitcoin reserve worth $20 billion.²⁵
Bitcoin Design
Bitcoin (BTC) is a digital currency with fine‑grained divisibility.
| Unit | Symbol | BTC Value | ‑ | Bitcoin | BTC / ₿ | 1 | ‑ | millibitcoin | mBTC | 0.001 | ‑ | bit | μBTC | 0.000001 | ‑ | satoshi | sat | 0.00000001 |
|---|
The smallest unit, the satoshi (1 × 10⁻⁸ BTC), supports micro‑transactions. Unicode symbol ₿ added in 2017.²⁷
Blockchain: Backbone
A distributed ledger chains blocks by hash (SHA‑256 × 2). Mining adds blocks through proof‑of‑work, rewarding miners with BTC + fees.²⁸
Addresses and Transactions
Each Bitcoin address derives from a key pair; types include Legacy (1…), P2SH (3…), SegWit (bc1…), and Taproot (bc1p…).²⁹³⁰ Transactions use digital signatures and timestamp servers to order blocks.³¹
Proof of Work & Network
Miners solve puzzles to add blocks; the longest chain reflects honest majority. Network steps: broadcast → verify → mine → propagate → confirm. Rewards and fees incentivize security; Merkle trees reduce disk space; SPV clients verify headers only — see diagram on page 13 of source PDF.:contentReference[oaicite:1]{index=1}
Privacy and Fungibility
Bitcoin is pseudonymous; privacy depends on address reuse and mixing tools like CoinJoin or Lightning Network.³²
Wallets
Hot wallets are online (apps); cold wallets are offline (devices/paper). Users secure seed phrases to protect private keys.³³ Scalability solutions such as Lightning Network and sidechains improve speed and cost.³⁴
Economics and Usage
Bitcoin embodies free‑market ideology and cypherpunk privacy principles.³⁵ Legality differs by nation: the U.S., EU, and Japan regulate under AML/tax laws; China and others ban it.³⁶
Payments
Economists like Kenneth Rogoff note Bitcoin thrives in the informal economy but rarely for daily commerce.³⁷ The E.U.’s MiCA Regulation and U.S. IRS rules define crypto as property/taxable asset.³⁸ Consumer agencies warn of fraud and volatility.³⁹ Research shows it’s used more as speculation than payment.⁴⁰
Cross‑border surveys by Jack Dorsey’s Block show 87% of holders use BTC for remittances.⁴¹ The Central African Republic (2022) and El Salvador (2021) experimented with legal tender status — both later adjusted their laws.⁴²⁴³⁴⁴
Investment
Institutional adoption accelerated (2020–2026). Robert Kiyosaki predicted $250 k BTC by 2026.⁴⁵ Elon Musk’s SpaceX moved 1 215 BTC ($133 m) in 2025.⁴⁶ Global crypto market cap surpassed $4 trillion in 2025.⁴⁷ El Salvador restructured its reserves for security.⁴⁸ SEC approved spot ETFs on Jan 10 2024, bringing crypto to Wall Street.⁴⁹ Pew Research Center (2024) found 17% of U.S. adults had used crypto.⁵¹ Corporate holders include MicroStrategy, GBTC, Tesla, and Block Inc.⁵³
Economic Bubble Debate
Jean Tirole, Joseph Stiglitz, Kenneth Rogoff, and Nouriel Roubini call Bitcoin a speculative bubble.⁵⁴⁵⁵⁵⁶⁵⁸ Powell (2024) called it “a rival to gold, not the dollar.” Stiglitz and Roubini criticized its volatility and crime risk.⁵⁷
Market Characteristics
Bitcoin trades 24/7, globally, with transparent, immutable transactions. Its ecosystem includes stablecoins, DeFi, and NFTs built on blockchain innovation.⁵⁹