What is the difference between a stack and a queue?

Stack (java.util.Stack) and Queue are two fundamental data structures with different principles of element access.

Feature	Stack (Stack)	Queue (Queue)
Principle	LIFO (Last-In, First-Out)	FIFO (First-In, First-Out)
Access	Add and remove from one end (top of stack)	Add from one end (tail), remove from another (head)
Operations	push (add), pop (remove), peek (view top without removing)	offer/add (add), poll/remove (remove), peek/element (view head without removing)
Examples of use	Function execution (call stack), depth-first search (DFS), undo operations	Background task processing, data buffers, breadth-first search (BFS)