What Is Queue in Data Structure and Its Types?


Scott Campbell

What Is Queue in Data Structure and Its Types?

In computer science, a queue is an abstract data type that follows the principle of FIFO (First-In-First-Out). It can be visualized as a line of people waiting for a service, where the person who joins first gets served first.

Queues are commonly used in various real-life scenarios, such as handling requests in operating systems, managing print jobs in a printer queue, or implementing message queues in distributed systems. Understanding queues and their types is essential for efficient data processing and management.

The Basic Queue Operations:

The two fundamental operations performed on a queue are:

  • Enqueue: Adding an element to the end of the queue.
  • Dequeue: Removing an element from the front of the queue.

The enqueue operation adds an element to the rear end of the queue, while the dequeue operation removes an element from the front end. These operations ensure that elements are processed in the order they were added.

Main Types of Queues:

There are several types of queues based on their characteristics and specific use cases. Let’s explore some commonly used ones:

1. Simple Queue:

A simple queue operates according to FIFO principles, where elements are added at one end and removed from the other. It allows operations like enqueue and dequeue but does not support any additional functionalities.

2. Circular Queue:

A circular queue overcomes one limitation of a simple queue, which is the wastage of space. In a circular queue, the last element points to the first element, creating a circular structure.

This allows efficient utilization of space as elements can wrap around and occupy empty spaces from dequeued elements.

3. Priority Queue:

In a priority queue, each element is assigned a priority value, and elements with higher priority are dequeued first. It can be implemented using various data structures like arrays, linked lists, or heaps.

4. Double-Ended Queue (Deque):

A double-ended queue supports insertion and deletion at both ends. It allows elements to be added or removed from either the front or rear end.

This flexibility makes it suitable for scenarios where elements need to be added or removed from both directions.


Queues are an essential concept in data structures and play a crucial role in various applications. Understanding different types of queues helps in choosing the right one for specific use cases and optimizing data processing efficiency.

Now that you have a better understanding of queues and their types, you can apply this knowledge to solve problems efficiently using appropriate queue implementations.

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