Bitcoin (₿) is a decentralized digital currency that can be transferred on the peer-to-peer bitcoin network.[7] Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain. The cryptocurrency was invented in 2008 by an unknown person or group of people using the name Satoshi Nakamoto.[10] The currency began use in 2009[11] when its implementation was released as open-source software.[6]: ch. 1
Bitcoin
Prevailing bitcoin logo
Denominations
Plural
bitcoins
Symbol
₿ (Unicode: U+20BF ₿ BITCOIN SIGN)[a]
Code
BTC,[b] XBT[c]
Precision
10−8
Subunits
1⁄1000
millibitcoin
1⁄1000000
microbitcoin
1⁄100000000
satoshi[2]
Development
Original author(s)
Satoshi Nakamoto
White paper
"Bitcoin: A Peer-to-Peer Electronic Cash System"[4]
Implementation(s)
Bitcoin Core
Initial release
0.1.0 / 9 January 2009 (13 years ago)
Latest release
22.0 / 13 September 2021 (8 months ago)[3]
Code repository
github.com/bitcoin/bitcoin
Development status
Active
Website
bitcoin.org
Ledger
Ledger start
3 January 2009 (13 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[7]
Block reward
₿6.25[d]
Block time
10 minutes
Circulating supply
₿18,925,000[e]
Supply limit
₿21,000,000[5][f]
Valuation
Exchange rate
Floating
Market cap
US$775 billion[g]
Demographics
Official user(s)
El Salvador[8]
Central African Republic[9]
The symbol was encoded in Unicode version 10.0 at position U+20BF ₿ BITCOIN SIGN in the Currency Symbols block in June 2017.[1]
Very early software versions used the code "BC".
Compatible with ISO 4217.
May 2020 to approximately 2024, halved approximately every four years
As of 2022-01-10
The supply will approach, but never reach, ₿21 million. Issuance will permanently halt c. 2140 at ₿20,999,999.9769.[6]: ch. 8
As of 2022-01-10
Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies, products, and services. Bitcoin has been criticized for its use in illegal transactions, the large amount of electricity (and thus carbon footprint) used by mining, price volatility, and thefts from exchanges. Some investors and economists have characterized it as a speculative bubble at various times.
Bitcoin, has been described as an economic bubble by at least eight Nobel Memorial Prize in Economic Sciences.[12] Journalists, economists, investors, and the central bank of Estonia have voiced concerns that bitcoin is a Ponzi scheme.[13][14][15][16]
The word bitcoin was defined in a white paper published on 31 October 2008.[4][17] It is a compound of the words bit and coin.[18] No uniform convention for bitcoin capitalization exists; some sources use Bitcoin, capitalized, to refer to the technology and network and bitcoin, lowercase, for the unit of account.[19] The Wall Street Journal,[20] The Chronicle of Higher Education,[21] and the Oxford English Dictionary[18] advocate the use of lowercase bitcoin in all cases.
A few local and national governments are officially using Bitcoin in some capacity, with two countries, El Salvador and the Central African Republic, adopting it as a legal tender.