Ontologies: Relational Vocabularies

Data managers, scientists, and others in the marine science community are used to working with controlled vocabularies, even if they know them by another name. After all, anyone working with a set of data described using an agreed-upon set of terms has been exposed to a controlled vocabulary.

Controlled vocabularies are a good tool: they are often simple to develop, can be used among a small community of users, and are easy to store, visualize, and access.

However, as projects and users require more data interoperability, more advanced data comparison, and better discovery, the limitations of simple vocabularies become more apparent. Ontologies provide additional functionality to meet these challenges.

Ontologies improve on simple vocabularies by allowing relationships between terms to be defined (e.g., "Sea Surface Temperature" is a kind of "Temperature"), and by providing a way for rules or properties to be defined for terms (e.g., an "estuary" must have a salinity of <33 psu).

Semantic technology, including the use of ontologies, paves the way for data interoperability, advanced search and discovery, and "machine reasoning" in a way that simpler technologies cannot support.

In this guide, we will explore the nature of ontologies and their applicability in marine science. First, we will explain exactly what an ontology is, including how it differs from a standard controlled vocabulary. Then we discuss the importance of ontologies, including their various strengths. We also provide a brief overview of the technologies which form the foundation of ontologies, including the RDF and OWL formats. Finally, we discuss various methods of developing, providing, and working with ontologies.

Suggested Citation

Alexander, P. 2011. "Ontologies: Relational Vocabularies." In The MMI Guides: Navigating the World of Marine Metadata. http://marinemetadata.org/guides/vocabs/ont. Accessed March 6, 2021.