In computer science, a cryptocurrency, crypto-currency, or crypto is a digital currency that does not rely on any central authority to uphold or maintain it. Instead, transaction and ownership data is stored in a digital ledger using distributed ledger technology, typically a blockchain. However, when a cryptocurrency is issued by a single issuer or minted or created prior to issuance, it is generally considered centralized.
Despite the name, cryptocurrencies are not considered to be currencies in the traditional sense and while varying treatments have been applied to them, including classification as commodities, securities, as well as currencies, cryptocurrencies are generally viewed as a distinct asset class in practice. Unlike paper money, cryptocurrency does not exist in physical form and is typically not issued by a central authority. Cryptocurrencies typically use decentralized control as opposed to a central bank digital currency (CBDC). Traditional asset classes like currencies, commodities, and stocks, as well as macroeconomic factors, have modest exposures to cryptocurrency returns.
The first modern cryptocurrency was Bitcoin, which was first released as open-source software in 2009. As of March 2022, there were more than 9,000 other cryptocurrencies in the marketplace, of which more than 70 had a market capitalization exceeding $1 billion.