A Bitcoin transaction is an exchange of Bitcoin from one party to another. It is recorded in the public ledger of all Bitcoin transactions known as the blockchain. In order for a transaction to be valid, it must be digitally signed using the sender’s private key and broadcast to the network. Once the transaction is broadcast, miners will race to validate the transaction and add it to the blockchain. Once the transaction is added to the blockchain, it is considered immutable, meaning it cannot be changed or reversed.