Just as ontology developed over the centuries as part of philosophy, so in recent years ontology has become intertwined with the development of the information sciences. Researchers in such areas as artificial intelligence, formal and computational linguistics, biomedical informatics, conceptual modeling, knowledge engineering and information retrieval have come to realize that a solid foundation for their research calls for serious work in ontology, understood as a general theory of the types of entities and relations that make up their respective domains of inquiry. In all these areas, attention has started to focus on the content of information rather than on just the formats and languages in terms of which information is represented. A clear example of this development is provided by the many initiatives growing up around the project of the Semantic Web. And as the need for integrating research in these different fields arises, so does the realization that strong principles for building well-founded ontologies might provide significant advantages over ad hoc, case-based solutions. The tools of Formal Ontology address precisely these needs, but a real effort is required in order to apply such philosophical tools to the domain of Information Systems. Reciprocally, research in the information science raises specific ontological questions which call for further philosophical investigations.