BitcoinBitcoinis a cryptocurrencyand worldwide payment system, It is the first decentralized digital currency, Instead of trust being mediated by a bank or other centralized financial institution, transactions take place directly between users, peer-to-peer, These transactions are verified by network nodesthrough the use of cryptography. Special nodes, called miners, record transactions toa public distributed ledgercalled a blockchain. Bitcoins are issued to miners as an incentive to attract their computing power to secure the network.Bitcoin can be exchanged for other currencies products, and services. As of February 2015, over 100,000 merchants and vendors accepted bitcoin as payment, Research produced by the University of Cambridgeestimates that in 2017, there are 2.9 to 5.8 million unique users using a cryptocurrencywallet, most of them using bitcoin. Bitcoin was invented by an unknown person or group of people under the name Satoshi Nakamotoand released as open-sourceEtymologyThe word bitcoin first occurred and was defined in the white paperthat was published on 31 October 2008, It is a compoundof the words bitand coin,The white paper frequently uses the shorter coin. There is no uniform convention for bitcoin capitalization. Some sources use Bitcoin, capitalized, to refer to the technology and networkand bitcoin, lowercase, to refer to the unit of account, The Wall Street Journal, The Chronicle of Higher Education, and the Oxford English Dictionaryadvocate use of lowercase bitcoin in all cases, a convention followed throughout this article.UnitsThe unit of account of the bitcoin system is bitcoin. As of 2014, ticker symbolsused to represent bitcoin are BTC[a]and XBT.[b]Its Unicodecharacter is Small amounts of bitcoin used as alternativeunits are millibitcoin (mBTC), bit and satoshi (sat). Named in homage to bitcoin's creator, a satoshi isthe smallest amount within bitcoin representing 0.00000001 bitcoins, one hundred millionth of a bitcoin. A bit equals 0.000001 bitcoins, one millionth of a bitcoin or 100 satoshis. A millibitcoin equals0.001 bitcoins, one thousandth of a bitcoin or 100,000 satoshis. HistoryOn 18 August 2008, the domain name "bitcoin.org" was registered. In November that year, a link to apaper authored by Satoshi Nakamototitled Bitcoin: A Peer-to-Peer Electronic Cash System was posted to a cryptography mailing list. Nakamoto implemented the bitcoin software as open source codeand released it in January 2009 on SourceForge. The identity of Nakamoto remains unknown. In January 2009, the bitcoin network came into existence after Satoshi Nakamoto mined the first ever block on the chain, known as the genesis block. Embedded in the coinbase of this block was the following text:The Times 03/Jan/2009 Chancellor on brink of second bailout for banks.