In Chapter 3 we discussed the concept of ontology and its characteristics, and the numerous advantages of ontologies. We may feel inspired to design an ontology for our information system but we still do not know: where to start, how to prepare ourselves, how many people are needed for the ontology design, how we ascertain that we are on the right track, whether similar ontologies already exist, how to determine that we are designing a valid ontology, what tool we can use to assist us with our design, and other similar issues.
There is not a single, consensual ontology-design methodology. Many different ontology design methodologies have been proposed. We will consider some of them in order to illustrate different approaches to ontology design. The methodologies presented are different from each other and together cover various aspects of the ontology design process.