What is the difference between a stack and a queue?

Stacks and queues are both data structures used to store collections of elements. However, they differ in how elements are added and removed:

– Stack: It follows the Last In, First Out (LIFO) principle. This means the last element added to the stack will be the first one to be removed. Operations are mainly `push` (to add an element to the top of the stack) and `pop` (to remove the top element of the stack). Stacks are useful in scenarios where you need to reverse things or want to remember the sequence of actions to backtrack, such as in browser history or undo functionalities in applications.

– Queue: It operates on the First In, First Out (FIFO) principle. The first element added to the queue will be the first one to be removed. The main operations are `enqueue` (to add an element to the end of the queue) and `dequeue` (to remove and return the front element of the queue). Queues are essential in scenarios where order needs to be preserved, like in printers’ spooling, customer service lines, or any process requiring processing in the order of arrival.

In summary, the primary difference lies in how elements are added and removed, reflecting in their application in various real-world scenarios.