What is cryptocurrency?

A cryptocurrency (or crypto currency) is a digital asset designed to work as a medium of exchange that uses cryptography to secure its transactions, to control the creation of additional units, and to verify the transfer of assets.[1][2][3] Cryptocurrencies are classified as a subset of digital currencies and are also classified as a subset of alternative currencies and virtual currencies. Cryptocurrencies use decentralized control[4] as opposed to centralized electronic money and central banking systems.[5] The decentralized control of each cryptocurrency works through a blockchain, which is a public transaction database, functioning as a distributed ledger.[6]

Bitcoin, created in 2009, was the first decentralized cryptocurrency.[7] Since then, numerous other cryptocurrencies have been created.[8] These are frequently called altcoins, as a blend of alternative coin.[9][10][11]