Cryptocurrency is a type of digital or virtual currency that uses encryption techniques to secure and verify transactions and control the creation of new units. Cryptocurrencies operate independently of a central bank and are decentralized, meaning they are not controlled by any government or financial institution.

Cryptocurrencies use blockchain technology, a decentralized ledger that records all transactions made with the currency. Each block in the chain contains a record of several transactions, and once a block is added to the chain, it cannot be altered or deleted.

Bitcoin, created in 2009, was the first and most well-known cryptocurrency, but there are now thousands of different cryptocurrencies in circulation. Some of the most popular cryptocurrencies besides Bitcoin include Ethereum, Litecoin, and Ripple.

Cryptocurrencies can be bought and sold on digital exchanges, and can also be used to make purchases at some merchants who accept them as payment. The value of cryptocurrencies can be highly volatile and can fluctuate rapidly, based on market demand and other factors.