Summary form only given. The emerging concept of semantic Web services aims at more sophisticated Web Service technologies: on basis of semantic description frameworks, intelligent mechanisms are envisioned for discovery, composition, and contracting of Web services. The tutorial explains the current state of the art in semantic Web services on basis of the Web service modeling ontology WSMO and related initiatives. Commencing from the vision and arising challenges for semantic Web services, the tutorial in detail explains the specifications of recent frameworks for semantic Web services and presents the Web service execution environment WSMX as the WSMO reference implementation. The tutorial consists of three main sections that subsequently provide a complete overview of semantic Web services and the latest status of WSMO. The tutorial addresses academic as well as industrial researches and developers that are working with Web services and are interested in semantic Web services.