Ontology involves discovering categories and fitting objects into them in ways that make sense. Since Aristotle, this task has become divided among the various discrete sciences. Most scientists don't think of what they do as ontology, but in many ways, it is exactly what Aristotle began over two thousand years ago. It is also something each of us does, every day. By prioritizing items in a list, we are assigning relationships among various things.
Ontology can be relatively simple or it can be quite complex.
Ontology becomes more complex, and even daunting, when we begin to grapple with large groups of objects with complex relationships among them. For instance, anyone who has attempted to outline the processes and components of even a relatively small enterprise, has experienced the brain-cramps that can come with complex ontology. Nonetheless, enterprise modeling has become a valuable tool in the realm of business process reengineering. By taking a snapshot of an entire enterprise at a given point in time, decisions can be made about the future structure of the organization based upon the ontologies revealed. But even after just a few months have passed, the snapshot is out of date and new efforts are required to create an accurate enterprise model.