# Queue

An introduction to the queue data structure that supports First In First Out operation. In this lesson, we will learn about the queue and its applications, and will answer a few programming questions.

## We'll cover the following

The queue is similar to the stack but with some fundamental differences. It’s an abstract data type with the following operations defined on it:

**Enque (Key):**Insert an element in the collection.

**Deque():**Remove the oldest added element from the collection.

**isEmpty():**Determine whether the queue is empty or not.

**isFull():**Determine whether the queue is full or not.

All of the above operations take O(1) time complexity. The queue can be implemented using a linked list and an array.

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