Search engines do not just match keywords. They understand that Paris is the capital of France, that France is in Europe, and that Europe is a continent. That structure comes from knowledge graphs, databases of entities and the relationships between them.

Nodes represent things: people, places, organizations, events. Edges represent relationships: born in, works for, located in. Together they form a network that machines can query and reason over.

Common knowledge graph uses

• Search result enrichment
• Recommendation systems
• Question answering
• Fraud detection
• Drug discovery

Building one is labour-intensive. Curated graphs like Wikidata rely on human editors and automated imports. Extracted graphs use NLP to pull relationships from text, but accuracy varies. Maintaining consistency as facts change remains an ongoing problem.