Hashing is process of converting any size of data into fix size of data by performing mathematical operations.
A message to be hashed is called input; the Algorithm is used to do so is called hash function; the output is called hash value.
There are many algorithm which used to generate hash value like MD5, SHA-1, SHA-256, Tiger etc.
Hash function generates a unique value, this means two input always generates different hash value.
Hash value can not be decrypt once it’s hashed, this is the difference between encryption and hash.
Encrypted value can be decrypt using keys but we can not extract input from Hash value.
Common use of Hash is to store password into database.