In computer science, a hash table is an associative array data structure that associates keys with values. The primary operation it supports efficiently is a lookup, where it is given a key, an identifier for the information to be found such as a person's name, and asked to find the corresponding value. It works by transforming the key using a hash function into a hash, a number that the hash table uses to locate the desired value. In computer science, a hash table is an associa