Bitcoin is both a protocol and a cryptocurrency. Bitcoin (with a capital letter B), is a protocol that utilizes and implements a widely accessible, public, permanent, and decentralized ledger. Any user who has (i.e., controls) an entry in the ledger, is allowed to add to it. The Bitcoin protocol defines an entry, in this respect, as indicating an amount of a token (bitcoin with a minuscule b).

Bitcoin (in the latter sense) is the currency a decentralized peer-to-peer cryptocurrency that is supported by its users with no central authority or middlemen. It was first introduced in 2009 by Satoshi Nakamoto (as the world’s first cryptocurrency). Bitcoin has since become one of the most popular cryptocurrencies in the market, and in terms of market capitalization, it holds the top slot amongst other coins. It has small units or denominations known as satoshis, named after the inventor. A satoshi is equivalent to 0.00000001 bitcoin.