Directed Graph
Domain: Data Structures
🎯 Motivation
When relationships have a direction — one-way streets, followers on social media, prerequisites — edges point from one node to another.
📋 Concrete Example
Instagram follows: Alice follows Bob, but Bob does not follow Alice. The edge goes A -> B, not B -> A.
🔗 Analogy
One-way streets in a city. You can drive from street A to street B, but not back. The arrow shows the legal direction of travel.