Cryptocurrencies are digital or virtual currencies that use cryptography for security. They operate on decentralized networks, typically based on blockchain technology, meaning they are not controlled by a central authority like a bank. Transactions are recorded in a public and distributed ledger.

Created as alternatives to traditional currencies, cryptocurrencies like Bitcoin and Ethereum have gained popularity as means of exchange, investment, and store of value. Their volatility and decentralized nature present both opportunities and risks for users.