Stack vs Queue
Stack vs queue compared — LIFO vs FIFO, operations and use cases, with interactive visualizers for both.
A stack is last-in, first-out (LIFO); a queue is first-in, first-out (FIFO). Both add and remove in O(1) — the difference is which end you take from.
Stack vs Queue at a glance
| Stack | Queue | |
|---|---|---|
| Order | LIFO | FIFO |
| Add / remove | Same end (top) | Opposite ends |
| Used in | Undo, recursion, DFS | Scheduling, buffering, BFS |
| Complexity | O(1) | O(1) |
When to use Stack
Use a stack when the most recent item should be handled first — undo, call stacks, DFS.
When to use Queue
Use a queue when items should be handled in arrival order — task scheduling, BFS, buffers.
Tools for Stack & Queue
Stack Visualizer
Interactive LIFO stack — push and pop with an animated top pointer and step controls. Runs in your browser.
Open toolQueue Visualizer
Interactive FIFO queue — enqueue and dequeue with animated front/rear pointers and step controls. Runs in your browser.
Open toolLinked List Visualizer
Interactive singly linked list — insert head/tail, search, delete with animated pointer traversal and step controls. Runs in your browser.
Open toolHash Table Visualizer
Interactive hash table with separate chaining — insert, search, delete with animated hashing and collision chaining. Runs in your browser.
Open toolStack vs Queue
What is the difference between a stack and a queue?
A stack removes the most recently added item first (LIFO); a queue removes the oldest first (FIFO). Both are O(1) to add and remove.