Part A contains introductory material for the core of the book. After the outline, in Chap. 1, the notion of enterprise ontology, in the context of ontology in general and of the observed societal needs for enterprise ontology, is discussed in Chap. 2. It turns out that the notion of enterprise ontology could be beneficial not only for managers and designers of organizations and information systems, but also for the employees and the clients of an enterprise, be it a commercial company or a government agency. In Chap. 3 this notion is exemplified, taking the operational activities of becoming a member of a tennis club as the leading example. Despite the small size of this enterprise, you will acquire a basic knowledge of enterprise ontology that is appropriate and sufficient to study the remainder of the book.