Ontology

The field of ontology studies existing things as things, regarding what things exist, in what manner they exist, and the relations that hold between things.

An ontology is a representation of a domain of things, providing a consistent taxonomy of those things and defining what they are. An ontology can describe different portions of reality at differing levels of generality and granularity. A top-level domain ontology, for example, intends to bring every existing thing within its scope. A lower-level domain ontology, such as a modular suite or an application, focuses on a narrower range of natural or artificial objects, such as plants or documents, or a cardiovascular process or an act of selling.

The field of ontology is interdisciplinary. It was historically formulated within philosophy, but now is at the heart of information systems and principles in database management. While ontology can be informed by principles derived from philosophy,  the practical application is borne out in the fields like biomedical informatics (e.g., genomic data, electronic health records, etc.), web search services (e.g., Siri, Amazon, etc.), and military intelligence (e.g., unified planning and operations manuals, tracking terrorist activity, etc.).

Ontology Projects