In a philosophical context 0:28
Why ontology is important 1:08
Ontological materialism 1:34
Ontological idealism 1:59
In a non-philosophical context 2:24
Information systems 2:40
Social ontology 3:25

The word ontology comes from two Greek words: "Onto", which means existence, or being real, and "Logia", which means science, or study. The word is used both in a philosophical and non-philosophical context.

ONTOLOGY IN A PHILOSOPHICAL CONTEXT
In philosophy, ontology is the study of what exists, in general. Examples of philosophical, ontological questions are: What are the fundamental parts of the world? How they are related to each other? Are physical parts more real than immaterial concepts? For example, are physical objects such as shoes more real than the concept of walking? In terms of what exists, what is the relationship between shoes and walking?

Why is ontology important in philosophy?
Philosophers use the concept of ontology to discuss challenging questions to build theories and models, and to better understand the ontological status of the world.

Over time, two major branches of philosophical ontology has developed, namely: Ontological materialism, and ontological idealism.

Ontological materialism
From a philosophical perspective, ontological materialism is the belief that material things, such as particles, chemical processes, and energy, are more real, for example, than the human mind. The belief is that reality exists regardless of human observers.

Ontological idealism
Idealism is the belief that immaterial phenomenon, such as the human mind and consciousness, are more real, for example, than material things. The belief is that reality is constructed in the mind of the observer.

ONTOLOGY IN A NON-PHILOSOPHICAL CONTEXT
Outside philosophy, ontology is used in a different, more narrow meaning. Here, an ontology is the description of what exist specifically within a determined field. For example, every part that exists in a specific information system. This includes the relationship and hierarchy between these parts.
Unlike the philosophers, these researchers are not primarily interested in discussing if these things are the true essence, core of the system. Nor are they discussing if the parts within the system are more real compared to the processes that take place within the system. Rather, they are focused on naming parts and processes and grouping similar ones together into categories.

Outside philosophy, the word ontology is also use, for example, in social ontology. Here, the idea is to describe society and its different parts and processes. The purpose of this is to understand and describe the underlying structures that affect individuals and groups.

Suggested reading
You can read more about ontology in some of the many articles available online, for example:
http://www.streetarticles.com/science...

Copyright
Text and video (including audio) © Kent Löfgren, Sweden