# What Is Queue in Data Structure Simple Definition?

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Angela Bailey

What Is Queue in Data Structure Simple Definition?

A queue is a fundamental data structure in computer science that follows the First-In-First-Out (FIFO) principle. It is an abstract concept that represents a collection of elements where the addition of new elements happens at one end, known as the rear or tail, and the removal of existing elements occurs at the other end, called the front or head.

Key Features of a Queue:

• Queue operates on a strict order of insertion and removal.
• The element that is inserted first will be the first one to be removed.
• New elements are added to the rear of the queue.
• Existing elements are removed from the front of the queue.

Real-life Analogy:

To better understand how queues work, think of a real-life scenario – standing in line at a grocery store. The person who arrives first will be served first, while those who arrive later have to wait until it’s their turn. Similarly, a queue data structure works on this principle.

Operations on a Queue:

A queue typically supports two main operations:

To add an element to the rear/tail of a queue, we use the enqueue operation. This operation increases the size of the queue by one and places the new element in its appropriate position.

### Removal (Dequeue):

To remove an element from the front/head of a queue, we use the dequeue operation. This operation decreases the size of the queue by one and returns/removes the element that has been in the queue the longest.

Applications of Queue:

• Job scheduling in operating systems
• Handling requests in web servers
• Implementing caches and buffers
• Simulation of real-world scenarios like a waiting line or traffic flow

Types of Queue:

### Circular Queue:

A circular queue is a variation of a regular queue where the last element points back to the first element. This eliminates the need for shifting elements when the front or rear reaches the end of the underlying array.

### Priority Queue:

A priority queue assigns a priority value to each element and dequeues elements based on their priority. Elements with higher priorities are dequeued first. It is commonly used in scenarios where some elements are more important than others.

In conclusion, a queue is an essential data structure that follows the FIFO principle and is commonly used in various applications. Understanding its simple definition, operations, and types can greatly benefit programmers when solving real-world problems efficiently.