When the investment pays back
Where ontology pays back the investment
- Interoperability across systems — same meaning, different stores. The use case the W3C built the stack for.
- Automated reasoning — a reasoner finds inconsistencies and derives facts you didn't write — at scale, deterministically.
- Data quality — formal constraints (OWL + SHACL) catch silent corruption that schema-only systems miss.
- Grounding AI — LLM hallucinations drop sharply when the model is forced to ground its claims in an ontology-typed KG (see the KG-RAG track).
- Decade-scale longevity — a published ontology with stable IRIs survives three database migrations and two cloud providers.
If none of the five apply, don't build an ontology. Build a schema and move on.