Hash

A hash is a cryptographic function used as part of the hashing process whereby a string of arbitrary data is passed through a function, producing an output of a fixed size. Hashing relies on one-way functions, meaning that the computation is easy to perform but practically infeasible to reverse, i.e., from the hash to the original data. Hashes and hashing are used extensively in blockchains and blockchain-like systems, including Proof of Work mining.