What Is the Queue Data Structure and Its Types?


Heather Bennett

The queue data structure is a fundamental concept in computer science. It follows the First-In-First-Out (FIFO) principle, where the first element to be inserted is the first one to be removed. In this article, we will explore what a queue is and its different types.

What Is a Queue?

A queue is an abstract data type that represents a collection of elements. It resembles a real-life queue such as people waiting in line at a ticket counter or a printer managing print jobs. The two primary operations performed on a queue are:

  • Enqueue: Adds an element to the end of the queue.
  • Dequeue: Removes an element from the front of the queue.

Main Types of Queues

1. Linear Queue

A linear queue, also known as a simple queue, is the most basic type of queue.

It has two pointers – front and rear – that keep track of the first and last elements, respectively. Elements are enqueued at the rear and dequeued from the front.

2. Circular Queue

In a circular queue, both ends are connected, forming a circular structure.

This allows efficient space utilization as elements wrap around when reaching the end of the queue. The front and rear pointers move in a circular manner, ensuring continuous access to elements.

3. Priority Queue

A priority queue assigns priority values to each element and dequeues them based on their priority level rather than their position in the queue. Elements with higher priority values are dequeued before those with lower priority values.

4. Deque (Double-ended Queue)

A deque, also known as a double-ended queue, allows insertion and deletion at both ends.

This means elements can be enqueued and dequeued from both the front and rear. It provides more flexibility than a linear queue.

5. Circular Deque

A circular deque is an extension of a circular queue that allows insertion and deletion at both ends. Similar to a circular queue, it enables efficient space utilization by wrapping around when necessary.


In conclusion, a queue is an essential data structure that follows the First-In-First-Out (FIFO) principle. Understanding the different types of queues can help in designing efficient algorithms for various applications. Whether you need a simple linear queue or a more complex priority queue or deque, choosing the right type depends on your specific requirements.

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