In computing, a hash table is a map of keys to values. It is a data structure used to implement an associative array. It uses a hash function to compute an index into an array of slots, from which desired value can be fetched.

A hash table is a data structure that stores key-value pairs. It uses a hashing function to compute an index into an array of buckets or slots, from which the desired value can be found. Hash tables offer efficient insertion, deletion, and retrieval operations, typically with an average time complexity of O(1) for each operation, making them suitable for tasks such as indexing and fast data lookup.

Here’s a breakdown of key points:

Key-Value Storage: Hash tables store data in key-value pairs, where each key is unique.
Hashing Function: A hashing function is used to compute a unique index (hash code) for each key. This index determines the location in the underlying array where the value associated with the key will be stored.
Array of Buckets/Slots: Hash tables typically consist of an array (often called a bucket array) where elements are stored based on their hash codes.
Collision Handling: Since different keys can sometimes produce the same hash code (collision), hash tables need a mechanism to handle such cases. Common methods include chaining (storing multiple values at the same index) or open addressing.
Fast Operations: Hash tables provide fast operations for insertion, deletion, and retrieval of data, with an average time complexity of O(1) for each operation under ideal circumstances.
Usage: Hash tables are widely used in various applications such as database indexing, caches, symbol tables in compilers, and associative arrays in programming languages.

In an interview, it’s beneficial to elaborate on these points, discussing how hash tables work internally, their advantages, limitations (such as potential collisions and how they are mitigated), and common use cases.