Ontologies are formal systems for representing the world in a way that can be used both by people and computers.
Ontologies represent the world as ‘entities’ and their ‘relationships’ with other entities. Entities and relationships are grouped into classes according to shared characteristics.
Entities include:
- things that exist over time, such as objects (e.g., human beings) and places (e.g. countries),
- things that inherently involve change over time, such as processes (e.g., behaviour), and
- characteristics of things (e.g., age).
Relationships can be anything that connects two entities. The most important relationship that every entity should have is the ‘subclass of’ relationship (also referred to as 'is a' or 'has parent class'). This tells us what kind of a thing the entity is.
For example, ‘behaviour change intervention’ in BCIO is a subclass of ‘intervention’ which is a subclass of ‘planned process’.
Every entity in an ontology should have:
- a unique ID (preferably in the form of a URL or web link so that users can find it on the internet),
- a label (a human interpretable word or phrase that can be used in documents to refer to the entity),
- a formal definition, (a precise specification of the entity), and
- its parent class (i.e. what it is an immediate subclass of).
With this structure, we can represent the world in a way that is clear, coherent and consistent by creating a network of entities linked by their relationships.
For a brief introduction to ontologies, see https://www.ontotext.com/knowledgehub/fundamentals/what-are-ontologies/
A glossary of terms is available in the Resources Section of the HBCP website.
