Tape Storage is the first kind of storage and the oldest technology in electronic data storage.

Direct Attached Storage (DAS) refers to digital storage system directly attached to server(s) or workstation(s) without a network connecting them.

Storage Area Network (SAN) is a kind of storage that is more sufficient in case or situation in which the user needs high speed and good enough performance

Unified Storage was called by this name because of its primary benefit that it combining between NAS and SAN Storage.