Hash function

{wiki}

= Hash
{synonym}

Applications:
* https://en.wikipedia.org/wiki/Hash_table[hash map] which is a O(1) amortized implementation of a map
* creating unbreakable chains of data, e.g. for https://stackoverflow.com/questions/22968856/what-is-the-file-format-of-a-git-commit-object-data-structure/37438460#37438460[Git commits] or <Bitcoin>. 
* storing passwords on a server in a way that if the password database is stolen, attackers can't reuse them on other websites where the user used the same password: https://security.blogoverflow.com/2013/09/about-secure-password-hashing/
