What is a hash value?
Values returned by a so called hash function are called hash values (or also hash codes, digests or simply hashes). Hash functions are any algorithm that transforms data of arbitrary size into data that is of a fixed size. They can be used in computer programs for fast data lookups. They accelerate the table and database lookups by detecting duplicated records in large files. Hash functions are also very useful in cryptography, since they allow to easily verify that some input data maps to a given hash value while protecting the original input for example a plain text password that should stay secret.