Cryptocurrencies like Bitcoin emerged as a side product of attempts to create digital cash without a central authority. Satoshi Nakamoto invented Bitcoin in 2008 to solve the problem of how to achieve consensus about transaction records in a decentralized peer-to-peer network without central oversight. Cryptocurrencies use cryptography and a public ledger called a blockchain to securely record transactions and generate new units of currency through a process called mining, where computers validate transactions by solving complex math problems. This allows cryptocurrencies to operate as decentralized digital currencies without central control.