Bitcoin is a cryptocurrency and a digital payment system[14]:3 invented by an unknown programmer, or a group of programmers, under the name Satoshi Nakamoto.[15] It was released as open-source software in 2009.[16]

The system is peer-to-peer, and transactions take place between users directly, without an intermediary.[14]:4 These transactions are verified by network nodes and recorded in a public distributed ledger called the blockchain. Since the system works without a central repository or single administrator, bitcoin is called the first decentralized digital currency.[14][17]

Besides being obtained by “mining”, bitcoins can be exchanged for other currencies,[18] products, and services (legal or illegal ones).[19][20]

As of February 2015, over 100,000 merchants and vendors accept bitcoin as payment.[21] According to a research produced by Cambridge University in 2017, there are 2.9 to 5.8 million unique users actively using a cryptocurrency wallet, most of them using bitcoin.[22]

Bitcoin logo.svg

Etymology and orthography[edit]

The word bitcoin occurred in the white paper that defined bitcoin published in 2008. It is a compound of the words bit and coin.[23] The white paper frequently uses the shorter coin.[24]

There is no uniform convention for bitcoin capitalization. Some sources use Bitcoin, capitalized, to refer to the technology and network and bitcoin, lowercase, to refer to the unit of account.[25] The Wall Street Journal,[26] The Chronicle of Higher Education,[27] and the Oxford English Dictionary[23] advocate use of lowercase bitcoin in all cases, which this article follows.