Hashing

1. When referring to databases, hashing is a method of sorting and indexing data. The idea behind hashing is to allow large amounts of data to be indexed using keywords or keys commonly created by complex formulas. Hashing allows for large amounts of information to be quickly searched and listed.
2. When referring to security, hashing is a method of taking data, encrypting it, and creating unpredictable, irreversible output. There are many different types of hashing algorithms. MD2, MD5, SHA and SHA-1 are examples of hashing algorithms.

Also see: Algorithm