Bitcoin (BTC) is a peer-to-peer cryptocurrency, originally described in a 2008 paper by the pseudonymous Satoshi Nakamoto. Launched in January 2009, it was the world’s first cryptocurrency and remains the most popular, with the highest market capitalization of all cryptocurrencies. Bitcoin was built on several key innovations. Firstly, Nakamoto guaranteed that Bitcoin transactions were immutable, by recording all transactions on a distributed ledger known as a blockchain. Secondly, he ensured Bitcoin’s scarcity by capping the total number of Bitcoin in existence at 21 million. Finally, the community was incentivized to verify transactions by receiving rewards in the form of “mined” Bitcoin for checking the accuracy of the blockchain.