Written by experts in the field, this book addresses theoretical, formal, and pragmatic issues of geographic knowledge representation and integration based on an ontological approach. The first section sets the context by emphasizing the importance of philosophical, cognitive, and formal theories in preserving the semantics of geographic concepts during ontology development and integration. Section two exhausts all theoretical issues related to the subject and section three introduces a number of formal tools. Section four introduces a general method with the necessary steps to ontology integration and applies it to a number of ontology integration cases.