Bitcoin mining is a peer-to-peer computer process used to secure and verify bitcoin transactions-payments from one user to another on a decentralized network. Mining involves adding bitcoin transaction data to the global public ledger of Bitcoin's past transactions. Each group of transactions is called a block. Blocks are guaranteed by miners Bitcoin and build each other form a chain. This past transaction ledger is called blockchain. Blockchain serves to confirm transactions to other networks as they have occurred. Bitcoin nodes use blockchain to differentiate valid Bitcoin transactions from attempts to refinance coins that have been issued elsewhere.