Proof-of-work

Proof of work (PoW) is a cryptographic proof in which one party proves to others (verifiers) computational effort has been expended to solve cryptographic puzzle.  After the solution is found, verifiers can subsequently confirm this expenditure with minimal effort on their part. With Bitcoin, proof of work is able to establish consensus. Miners use their computing power to solve the puzzle that is able changes in difficulty with time. Once the puzzle is solved, it is published to the other miners (verifiers) who are able to verify the solution is accurate.  It is through this methods that blocks are formed on the blocked and consensus is reached by the miners to ensure the transactions on the Bitcoin ledger are accurate.