What is Ontology

Ontology is the study of “what exists” and the relationships between different kinds of existence. It can mean slightly different things depending on context:

Philosophy

In philosophy, ontology is a branch of metaphysics concerned with the nature of being, existence, and reality. It asks: - What kinds of things exist? (e.g., numbers, minds, matter, time, universals, etc.) - How are these things grouped and related? - What does it mean to be?

For example, an ontological question is: “Do abstract objects like numbers really exist, or are they just human inventions?”

Computer Science / Information Systems

In computing and AI, an ontology is a structured way of representing knowledge about a domain. It usually consists of: - Entities (or concepts): e.g., Person, Car, City. - Attributes: e.g., a Person has a name, age. - Relationships: e.g., a Person lives in a City.

Ontologies make data machine-readable and interoperable, often used in the Semantic Web, knowledge graphs, and AI reasoning.

Everyday Use

Sometimes people use “ontology” more loosely to mean “the set of categories and relationships we use to describe a system or worldview.”