Answer Description
A hash value, hashed value or just a hash is the result of a one-way cryptographic function. Hashes are used to verify the integrity of data (e.g. a file download) as well as to store sensitive data such like passwords.
Wikipedia
A cryptographic hash function (CHF) is a mathematical algorithm that maps data of arbitrary size (often called the "message") to a bit array of a fixed size (the "hash value", "hash", or "message digest") It is a one-way function, that is, a function which is practically infeasible to invert or reverse the computation Ideally, the only way to find a message that produces a given hash is to attempt a brute-force search of possible inputs to see if they produce a match, or use a rainbow table of matched hashes Cryptographic hash functions are a basic tool of modern cryptography
Cryptographic_hash_function - Wikipedia, the free encyclopedia