Cryptocurrency is a digital or virtual currency that uses cryptography for security and operates independently of a central bank. Cryptocurrencies use decentralized technology, called blockchain, to manage and record transactions. Unlike traditional currencies, such as the U.S. dollar or euro, cryptocurrencies are not backed by any government or financial institution, and their value is determined by the supply and demand in the market. Some of the most popular cryptocurrencies include Bitcoin, Ethereum, Litecoin, and Rippl.