Bitcoin (abbreviation: BTC or XBT; sign: ₿) is the first decentralized cryptocurrency. Nodes in the peer-to-peer bitcoin network verify transactions through cryptography and record them in a public distributed ledger, called a blockchain, without central oversight. Consensus between nodes is achieved using a computationally intensive system based on proof-of-work called mining. Bitcoin mining requires increasing quantities of electricity and was responsible for 0.2% of world greenhouse gas emissions as of 2022.Based on a free market ideology, bitcoin was invented in 2008 by Satoshi Nakamoto, an unknown person. Use of bitcoin as a currency began in 2009, with the release of its open-source implementation.: ch. 1  In 2021, El Salvador adopted it as legal tender. Bitcoin is currently used more as a store of value and less as a medium of exchange or unit of account. It is mostly seen as an investment and has been described by many scholars as an economic bubble. As bitcoin is pseudonymous, its use by criminals has attracted the attention of regulators, leading to its ban by several countries as of 2021. Source: Wikipedia (en)