Bitcoin is a cryptographic currency

Bitcoin is a cryptographic currency and a peer-to-peer payment system invented by Satoshi Nakamoto, which announces the invention in 2008 and publishes Open-source software in 2009.

Its unit of account is the bitcoin, limited to 21 million units and divisible to the eighth decimal place. All transactions are verified by the nodes of the network and recorded in a public registry deemed tamper-proof, called "blockchain". The system operates without central authority or single administrator, but in a decentralized manner thanks to the consensus of all the nodes of the network. Bitcoin is the largest decentralized cryptographic currency with a capitalization of approximately 46 billion euros in June 20172.

Bitcoins are created according to the source code of the software, in return for transaction processing. Some users use their computing power to verify, save, and secure transactions in the block chain. This activity, known as mining, allows participants to be remunerated, for each new validated block, by newly created bitcoins and the costs of the transactions processed3. Bitcoins can then be exchanged for other currencies, goods or services. The price of crypto-currency is fixed mainly on specialized market places and fluctuates according to the law of supply and demand.

As a means of payment, Bitcoin is accepted by a growing number of merchants4, incited by transaction costs generally lower than 2 to 3% charged by credit card organizations and oscillating, for the Bitcoin system, between 0 and 2 % Of transaction amount5. Unlike credit cards, any costs are borne by the buyer (not the seller), who chooses to pay voluntarily. A bitcoin transaction is irrevocable and can not be undone. Despite a 500% increase in the number of merchants accepting the bitcoin in 20146, crypto-currency is not yet very established in the retail trade but continues to take root in trade.

Since its creation in 2009 and until the closure by US authorities of Silk Road in 2013, Bitcoin has been used mainly as a means of exchange by criminal networks for gambling, buying illegal substances and Pirated data. Crypto-money has attracted the attention of financial regulators, 7 legislative bodies in various countries, notably the United States, and the media. However, in recent years, crypto-currency has matured and a growing number of studies conclude that these illegal activities, although still in existence as in any payment system, now represent only a minority crypto-monnaie10,11. The US Senate also recognizes that bitcoin provides perfectly legitimate financial services12.

The official monetary symbol "BitcoinSign.svg" was deposited and accepted in 2015 from Unicode13,14. The corresponding symbols used by the trading platforms are "BTC" and "XBT". Among the unofficial symbols used are "฿" and "Ƀ".