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Bitcoin
Bitcoin logo.svg
Prevailing bitcoin logo
Denominations
Plural	bitcoins
Symbol	₿[a]
Ticker symbol	BTC, XBT[b]
Subunits	
 ​1⁄1000	millibitcoin[1]
 ​1⁄100000000	satoshi[3]
Coins	Unspent outputs of transactions (in multiples of a satoshi)[4]:ch. 5
Development
Original author(s)	Satoshi Nakamoto
White paper	Bitcoin: A Peer-to-Peer Electronic Cash System[5]
Reference implementation	Bitcoin Core
Initial release	0.1.0 / 9 January 2009 (9 years ago)
Latest release	0.15.1 / 11 November 2017 (2 months ago)
Website	bitcoin.org
Ledger
Ledger start	3 January 2009 (9 years ago)
Timestamping scheme	Proof-of-work (partial hash inversion)
Hash function	SHA-256
Issuance	Block reward[6][7]
Block reward	₿12.5[c]
Block time	10 minutes
Block explorer	blockchain.info
Circulating supply	₿16,770,512 (as of 29 December 2017)
Supply limit	₿21,000,000
Valuation
Exchange rate	Increase US$14.516 thousand (as of 29 December 2017)
Market cap	Increase US$243.4 billion (as of 29 December 2017)
Jump up ^ The symbol was encoded in Unicode version 10.0 at position U+20BF ₿ BITCOIN SIGN in the Currency Symbols block in June 2017.[2]
Jump up ^ Compatible with ISO 4217.
Jump up ^ July 2016 to approximately June 2020, halved approximately every four years
This article contains special characters. Without proper rendering support, you may see question marks, boxes, or other symbols.
File:Bitcoin explained in 3 minutes.webm
Bitcoin explained in 3 minutes
Bitcoin is a cryptocurrency and worldwide payment system.[8]:3 It is the first decentralized digital currency, as the system works without a central bank or single administrator.[8]:1[9] The network is peer-to-peer and transactions take place between users directly, without an intermediary.[8]:4 These transactions are verified by network nodes through the use of cryptography and recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unknown person or group of people under the name Satoshi Nakamoto[10] and released as open-source software in 2009.[11]

Bitcoins are created as a reward for a process known as mining. They can be exchanged for other currencies,[12] products, and services. As of February 2015, over 100,000 merchants and vendors accepted bitcoin as payment.[13] Research produced by the University of Cambridge estimates that in 2017, there are 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.[14]