What is an Ontology Vocabulary?
Vocabularies are shared sets of terms (classes and properties) that ontologies reuse to describe common concepts. Using well-known vocabularies makes your data interoperable with the rest of the Semantic Web.
RDFS (RDF Schema)
The foundational vocabulary for defining classes and properties in RDF. Provides rdfs:Class, rdfs:subClassOf, rdfs:label, rdfs:comment, rdfs:domain, and rdfs:range. Almost every ontology uses RDFS terms.
Dublin Core (DC / DCTerms)
A set of 15 core metadata elements (title, creator, date, subject, etc.) widely used in libraries, digital repositories, and ontology metadata. The dcterms: namespace provides refined versions with formal ranges and domains.
@prefix dcterms: <http://purl.org/dc/terms/> .
<http://example.org/my-ontology>
dcterms:title "My Ontology"@en ;
dcterms:creator "Jane Doe" ;
dcterms:license <https://creativecommons.org/licenses/by/4.0/> .SKOS (Simple Knowledge Organization System)
Designed for thesauri, classification schemes, and controlled vocabularies. Key terms include skos:Concept, skos:broader, skos:narrower, skos:prefLabel, and skos:altLabel.
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
ex:Animals a skos:Concept ;
skos:prefLabel "Animals"@en ;
skos:narrower ex:Mammals , ex:Birds .
ex:Mammals a skos:Concept ;
skos:prefLabel "Mammals"@en ;
skos:broader ex:Animals .FOAF (Friend of a Friend)
Describes people, their activities, and their relationships. Commonly used terms include foaf:Person, foaf:name, foaf:knows, and foaf:homepage.
Schema.org
A collaborative vocabulary backed by Google, Microsoft, Yahoo, and Yandex. It defines types for everyday things: products, events, organizations, recipes, reviews, and more. Used extensively in web pages for structured data and rich search results.
OWL (Web Ontology Language)
OWL itself provides vocabulary terms for formal ontology modeling: owl:Class, owl:ObjectProperty, owl:DatatypeProperty, owl:Restriction, owl:equivalentClass, owl:disjointWith, and many more.
PROV (Provenance)
Captures the provenance of data — who created it, when, from what sources, and through which processes. Key types: prov:Entity, prov:Activity, prov:Agent.
Other Notable Vocabularies
- DCAT — Data Catalog Vocabulary for publishing dataset metadata
- VANN — Vocabulary for annotating vocabulary descriptions
- VOID — Vocabulary of Interlinked Datasets for describing RDF datasets
- SSN / SOSA — Semantic Sensor Network / Sensor, Observation, Sample, and Actuator
- GeoSPARQL — Geographic information represented in RDF
- Time Ontology — W3C ontology for temporal concepts and relations
Vocabulary Summary
| Vocabulary | Prefix | Purpose |
|---|---|---|
| RDFS | rdfs: | Classes, properties, labels |
| Dublin Core | dcterms: | Metadata (title, creator, date) |
| SKOS | skos: | Thesauri, concept schemes |
| FOAF | foaf: | People and social networks |
| Schema.org | schema: | Web structured data |
| OWL | owl: | Formal ontology modeling |
| PROV | prov: | Data provenance tracking |
Finding Vocabularies
Before creating your own terms, check whether a suitable vocabulary already exists:
- Linked Open Vocabularies (LOV) — A curated catalog of reusable RDF vocabularies with search and usage statistics.
- prefix.cc — A community-maintained registry for looking up namespace prefixes and their IRIs.
- BARTOC — Basel Register of Thesauri, Ontologies & Classifications.