Miners Hashes

"When a transaction is broadcast, mining computers summarize its information into a fixed-length encrypted string called a hash, using the SHA-256 algorithm in Bitcoin. Miners combine transaction data and earlier hashes into a hierarchy that packages many transactions into a block, while repeatedly changing a randomly generated number called a nonce to search for a winning block hash. The winning miner seals the block, links it to the previous block, and receives a reward, while the computational difficulty makes altering the record expensive and detectable."