$BNB Bitcoin (₿, BTC, XBT[n 1]; from the English bit: unit of binary information and coin "piece of currency") is a cryptocurrency also known as cryptographic currency. In the case of the unit designation, it is written "bitcoin" and, in the case of the peer-to-peer payment system, it is written "Bitcoin"[1]. The idea was first presented in November 2008 by a person, or a group of people, under the pseudonym Satoshi Nakamoto[2],[3]. The source code of the reference implementation was published in 2009. The goal is to create a decentralized and peer-to-peer system in order to exchange monetary value while freeing itself from any third-party organization such as financial institutions[4]. It is also a cryptocurrency whose scarcity has been programmed due to halving[5] and the limited number of bitcoins to 21 million units.