A detailed review of a brief history, applications and contributions of the hash functions in today's cryptology are articulated here. The secured hash functions are applied in various fields to provide a secure data transfer and authentication of messages and other user linked information through a series of algorithms. From the establishment of the first hash function MD5, followed by SHA 1, this data encryption system has undergone several upgradations and advanced to SHA 2 and SHA 3, the details of which are discussed in this paper. The importance of the secure hash algorithm in network security and also the necessity to upgrade from SHA1 and SHA2 to the modern standards of SHA3 is also highlighted here.