Knowledge management is a scientific discipline that focuses on acquisition, representation, sharing and reuse of knowledge resources. Overall, there are tow main approaches of Knowledge management: the personalization approaches that focus on human resources and communication, and the codification approaches that emphasize the collection and organization of knowledge. In this context of knowledge engineering, ontologies are now widely used. Ontologies are adopted as solution in applications related to knowledge management, e-services, intelligent integration information, information retrieval, integration of databases; as well as in new emerging fields such as the Semantic Web. Due to the encouraging results of this adoption, an increasing attention has been focused on ontologies and Ontological Engineering.