Bitcoin (abbreviation: BTC;[a] sign: ₿) is the first decentralized cryptocurrency. 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 guarantees the security of the bitcoin blockchain. Mining consumes increasing quantities of electricity and has been criticized for its environmental effects.[5]
Bitcoin
Prevailing bitcoin logo
Logo
Denominations
Plural
Bitcoins
Symbol
₿
(Unicode: U+20BF ₿ BITCOIN SIGN)[1]
Code
BTC[a]
Precision
10−8
Subunits
1⁄1000
Millibitcoin
1⁄1000000
Microbitcoin
1⁄100000000
Satoshi[b][2]
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 (15 years ago)
Latest release
25.1 / 19 October 2023 (6 months ago)[3]
Code repository
github.com/bitcoin/bitcoin
Development status
Active
Written in
C++
Source model
Free and open-source software
License
MIT License
Ledger
Ledger start
3 January 2009 (15 years ago)
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[c]
Valuation
Exchange rate
Floating
Demographics
Official user(s)
El Salvador[4]
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Based on a free market ideology, bitcoin was invented in 2008 by Satoshi Nakamoto, an unknown person.[6] Use of bitcoin as a currency began in 2009,[7] with the release of its open-source implementation.[8]: ch. 1 In 2021, El Salvador adopted it as legal tender.[4] Bitcoin is currently used more as a store of value and less as a medium of exchange or unit of account. It is mostly seen as an investment and has been described by many scholars as an economic bubble.[9] As bitcoin is pseudonymous, its use by criminals has attracted the attention of regulators, leading to its ban by several countries as of 2021.[10]