Developed by the NSA (National Security Agency) of USA in 2001, the Secure Hash Algorithm (SHA) is a set of cryptographic hash functions, mathematical operations that “hash” data and return a result that a user can compare to a known hash value to determine whether or not the data has been tampered with. SHA-256 is a function included in the SHA-2 group, which improved upon the original SHA-1 group. 256 identifies the function, which is made unique by the number of bits in each word used in the hash, which is 32. It is much more fleshed out than most of the other variations in SHA, which is why it is used mainly in important digital exchanges, such as authenticating Linux software packages and verifying exchanges in Crypto Currencies. Many popular altcoins use SHA-256, as well as Bitcoin itself, to calculate proof-of-work in transactions. This proves that SHA-256 is the most powerful and secure algorithm to be developed and tested for the longest period of time so far.