Stack
Domain: Data Structures
🎯 Motivation
When you need last-in-first-out behaviour — undo history, back button, function calls — a stack is the right structure.
📋 Concrete Example
Python list as stack: stack = []; stack.append('a'); stack.append('b'); stack.pop() returns b (last added). Only the top is accessible.
🔗 Analogy
A stack of plates in the cafeteria. You can only take the top plate (last put down) and you can only add a new plate on top. You cannot pull from the bottom.