Proof of work (PoW) is a form of cryptographic proof in which one party (the miners) proves to others that a certain amount of a specific computational effort has been expended. Verifiers can subsequently confirm this expenditure with minimal effort on their part. Bitcoin miners perform PoW calculations using ASIC computers, solving SHA256 hashes. The entire Bitcoin network does in excess of 150,000,000,000,000,000,000 hashes per second. The purpose of proof-of-work algorithms is not proving that certain work was carried out or that a computational puzzle was “solved”, but deterring manipulation of data by establishing large energy and hardware-control requirements to be able to do so.