Ontology
An ontology, in computing, is a set of precise statements about one subject that fixes what its words mean and how things relate. It has classes, which are groups of things, like restaurants; properties, which link things or give facts about them, like where a place is; and individuals, which are the actual things, like one particular cafe.
Source: W3C, OWL 2 Web Ontology Language Primer (Second Edition), checked October 29, 2026
What Ontology means for your business
The word also names a branch of philosophy, the study of what exists, and that's the meaning most search results lead with. When people in search marketing say it, they mean the computing kind.
Schema.org, the set of labels most structured data for Google Search uses, has the same parts: types such as Dentist and Event, and properties such as areaServed and startDate. Its own docs say it isn't meant to be a universal ontology of the world.
You don't need to build an ontology to get found. We'd use the types and properties Schema.org already has, and fill them in with facts that match your site. If AI tools know your name but can't connect it to what you offer or where you work, spelling out how the facts about you fit together is where we'd begin.
Last reviewed October 29, 2026. All terms
How AI answers it today
On October 29, 2026, Google's AI Overview led with the philosophy meaning, citing Merriam-Webster, Wikipedia, YouTube and a Reddit thread, then gave the computing meaning from Tom Gruber's definition. ChatGPT gave both meanings, compared ontology with taxonomy and cited nothing.
Our run through ChatGPT and Google's AI Overview, October 29, 2026. A sample, not what every buyer sees.
Related terms in entities and the knowledge graph
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