**Chaining** is a technique used for avoiding collisions in [hash tables](https://www.educative.io/answers/what-is-a-hash-table).

A **collision** occurs when two keys are [hashed](https://www.educative.io/answers/what-is-hashing) to the same index in a hash table. Collisions are a problem because every slot in a hash table is supposed to store a single element.



## The chaining technique
In the chaining approach, the hash table is an array of [linked lists](https://www.educative.io/answers/what-is-a-linked-list) i.e., each index has its own linked list.

All key-value pairs mapping to the same index will be stored in the linked list of that index.

# The benefits of chaining

- Through chaining, insertion in a hash table always occurs in *O(1)* since linked lists allow insertion in constant time.

- Theoretically, a chained hash table can grow infinitely as long as there is enough space.

- A hash table which uses chaining will never need to be resized.


What is chaining in hash tables?

Chaining is a technique to resolve hash table collisions using linked lists, ensuring constant-time insertion.