Semantic Web services promise to automate tasks such as discovery, mediation, selection, composition, and invocation of services, enabling fully flexible automated e-business. Their usage, however, still requires a significant amount of human intervention due to the lack of support for a machine-processable description. In this book, Jos de Bruijn and his coauthors lay the foundations for understanding the requirements that shape the description of the various aspects related to Semantic Web services, such as the static background knowledge in the form of ontologies, the functional description of the service, and the behavioral description of the service. They introduce the Web Service Modeling Language (WSML), which provides means for describing the functionality and behavior of Web services, as well as the underlying business knowledge, in the form of ontologies, with a conceptual grounding in the Web Service Modeling Ontology. Academic and industrial researchers as well as professionals will find a comprehensive overview of the concepts and challenges in the area of Semantic Web services, the Web Services Modeling Language and its relation to the Web Services Modeling Ontology, and an in-depth treatment of both enabling technologies and theoretical foundations.