In recent years service‐orientation has increasingly been adopted as one of the main approaches for developing complex distributed systems out of reusable components called services. Realizing the potential benefits of this software engineering approach requires semi‐automated and automated techniques and tools for searching or locating services, selecting the suitable ones, composing them into complex processes, resolving heterogeneity issues through process and data mediation, and reduce other tedious yet recurrent tasks with minimal manual effort. Just as semantics has brought significant benefits to search, integration and analysis of data, semantics is also seen as a key to achieving a greater level of automation to service orientation. This has lead to research and development, as well as standardization efforts on semantic Web services. Activities related to semantic Web services have involved developing conceptual models or ontologies, algorithms and engines that could support machines in semi‐automatically or automatically discovering, selecting, composing, orchestrating, mediating and executing services. This chapter provides an overview of the area after nearly a decade of research. The main principles and conceptual models proposed thus far including OWL‐S, WSMO, and SAWSDL/METEOR‐S. The main approaches developed by the research community that are able to use these semantic descriptions of services to support some of the typical activities related to services and service‐based applications are described. Next, the ideas and techniques described through two applications that integrate semantic Web services technologies within real‐world application are illustrated. Finally, a set of key resources is provided that would allow the reader to reach a greater understanding of the field, and are the main issues that will drive the future of semantic Web services.