Undirected Graph
Domain: Data Structures
🎯 Motivation
When relationships are mutual — friendships, roads, connections — edges have no direction. If A connects to B, B connects to A.
📋 Concrete Example
Facebook friendships: if Alice is friends with Bob, Bob is also friends with Alice. The edge is A — B (no arrow).
🔗 Analogy
A two-way street. Traffic can flow in both directions. If you can get from A to B, you can also get from B to A.