In one way or other we want that our data should be secured from all types of attacks. In protecting the data from the attacks, hash code plays an important role. The main advantage of Hash  codes is that they cannot be backtracked , which means from the hash code we cannot obtain the original data , more from this hash code generate the fixed length data from any variable input string or data, which also makes difficult for the hackers to make guesses regarding original data.  In this paper we are reviewing the concept of Hashing algorithms like SHA-1,SHA-2 , SHA-3, MD5 and more.

Keywords: Secure Hash Algorithms, SHA, MD5, Data Security.