What Is a Software Ontology?

Open a mature codebase and grep for Customer. In billing, it means an active, paid account; in support, anyone who has sent an email; in analytics, a deduplicated household. The bug isn’t in one module, but in three teams misunderstanding they’re referring to the same thing.

A software ontology is a clearly defined, shared model of a domain that includes concepts, meanings, and relationships, documented and integrated with code. This article explains its role in Domain-Driven Design (DDD), why it exists, and how it functions as a mental model.