Set
Domain: Programming Fundamentals
🎯 Motivation
When you need to track unique items and don’t care about order - like collecting unique tags or checking membership.
📋 Concrete Example
tags = {'python', 'ai', 'code'}. Adding python again does nothing - duplicates are ignored. tags.add('web') adds it.
🔗 Analogy
A bucket of unique marbles - you can toss one in, but if an identical one is already there, it bounces out. No order, no duplicates.