# What Is the Difference Between Stack and Queue Data Structure?

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Larry Thompson

What Is the Difference Between Stack and Queue Data Structure?

When it comes to data structures, two commonly used concepts are stacks and queues. Both of them have their own unique characteristics and applications. In this article, we will explore the differences between these two data structures.

## Stack Data Structure

A stack is a linear data structure in which elements are inserted and removed from one end only, known as the top of the stack. This follows the Last-In-First-Out (LIFO) principle. Imagine a stack of books where you can only add or remove a book from the top.

Main operations supported by a stack:

• Push: Adds an element to the top of the stack.
• Pop: Removes and returns the element from the top of the stack.

Additional operations supported by a stack:

• Peek: Returns the element from the top of the stack without removing it.
• isEmpty: Checks if the stack is empty or not.

## Queue Data Structure

A queue is also a linear data structure, but unlike a stack, it follows the First-In-First-Out (FIFO) principle. Think of it as a queue of people waiting in line for their turn at a ticket counter. The person who arrives first gets served first.

Main operations supported by a queue:

• Enqueue: Adds an element to the back of the queue.
• Dequeue: Removes and returns the element from the front of the queue.

Additional operations supported by a queue:

• Peek: Returns the element from the front of the queue without removing it.
• isEmpty: Checks if the queue is empty or not.

## Differences Between Stack and Queue

The key differences between stacks and queues can be summarized as follows:

### Data Structure Principle:

A stack follows the Last-In-First-Out (LIFO) principle, whereas a queue follows the First-In-First-Out (FIFO) principle. This fundamental difference determines how elements are added and removed from each data structure.

### Insertion and Removal Operations:

In a stack, elements are inserted and removed from one end only (the top), while in a queue, elements are inserted at one end (the back) and removed from another end (the front).

### Accessing Elements:

In both stacks and queues, you can access elements using the peek operation. However, in stacks, peek returns the top element, whereas in queues, peek returns the front element.

### Real-World Analogy:

A stack can be compared to a stack of books or plates, where you add or remove items from the top only. On the other hand, a queue can be compared to people waiting in line for their turn at a ticket counter or an amusement park ride.

In summary, while both stacks and queues are linear data structures used to store and retrieve elements, they differ in their principles of operation and how elements are added or removed. Understanding these differences is crucial in choosing the appropriate data structure for a specific problem or application.