What is a hash table?

A hash table is a data structure that provides fast access to elements by key. It uses a hash function to convert the key into an array index where the value is stored. This allows insertion, search, and deletion operations to be performed in approximately constant time O(1).

Example: if you have a key "user123", the hash function converts it into a number, for example, 42, and the value is stored in the cell with index 42. When searching by the key "user123", you again get index 42 and quickly find the desired value.

Main points:

• Fast key-based access
• Collisions may occur when different keys produce the same index, which are resolved by chaining or open addressing methods
• Used in many programming languages to implement dictionaries and associative arrays.