Bitcoin has been called a cryptocurrency because it is decentralized and uses cryptography to control transactions and prevent double-spending, a problem for digital currencies. Once validated, every individual transaction is permanently recorded in a public ledger known as the blockchain. Payment processing is done by a network of private computers often specially tailored to this task. The operators of these computers, known as "miners", are rewarded with transaction fees and newly minted Bitcoins. New bitcoins are created at an ever-decreasing rate.
