Stack vs Queue — What's the Difference?

A stack is a Last-In-First-Out (LIFO) data structure where the most recently added item is removed first; a queue is First-In-First-Out (FIFO), where the earliest added item is removed first.

Why they differ

• A stack supports push (add) and pop (remove) operations, both at the same end
• A queue supports enqueue (add at the back) and dequeue (remove from the front) at opposite ends

How to choose

• Use a stack for undo/redo functionality, or tracking function calls (the call stack)
• Use a queue for processing tasks in the order they arrived, like a print queue or a background job processor

FAQ

What real-world example explains the difference best?

A stack is like a stack of plates — you take from the top. A queue is like a checkout line — first person in line is served first.