Bitcoin (BTC) is a digital currency first described in a 2008 paper by pseudonymous developer Satoshi Nakamoto, who called it a peer-to-peer, electronic cash system. Bitcoin creation and transfer is based on an open sourcecryptographic protocol and is not managed by any central authority. Each bitcoin is subdivided into 100 million smaller units called satoshis, defined by eight decimal places. Bitcoins can be transferred through a computer or smartphonewithout an intermediate financial institution.
The processing of bitcoin transactions is automated by servers called bitcoin miners. These servers communicate over an internet-based network and confirm transactions by adding them to a ledger which is updated and archived periodically. In addition to archiving transactions each new ledger update creates some newly-minted bitcoins. The number of new bitcoins created in each update is halved every 4 years until the year 2140 where this number will round down to zero. At that time no more bitcoins will be added into circulation and the total number of bitcoins will top out at 21 million bitcoins.
Bitcoin is accepted in trade by various merchants and individuals in many parts of the world. A large share of such commercial use is believed to be for illicit drug and gambling transactions. Although bitcoin is promoted as a digital currency, many commentators have criticized Bitcoin's volatile market value, relatively inflexible supply, and minimal use in trade.