A hash is a set of characters of a sufficiently large certain length, which, by mathematical transformations, is associated with a set of information of arbitrary size. Such a set is unique and inherent only in this range of information.
If changes are made to the incoming information, a new hash will be generated for it.
Hash is irreversible. It is not possible to restore the original information from the character set.
An important quality of hashing is the ability to convert any amount of information to a character string of a certain length.
Using hash functions is common for verifying the integrity of transmitted data, electronic digital signatures, working with large amounts of information, when storing keys and passwords, and encryption.