Cryptocurrency is a digital or virtual currency that uses cryptography for security. It operates independently of a central bank or government. Bitcoin, the first and most widely used cryptocurrency, was created in 2009. Other popular cryptocurrencies include Ethereum, Ripple, and Litecoin. These currencies can be bought and sold on various online platforms, and can also be used to purchase goods and services. However, the value of cryptocurrencies can be highly volatile and their use is not yet widely accepted.