Chapter II presented the main concepts underlying business services. Ultimately, as this book proposes, business services need to be decomposed into networks of executable Web services. Web services are the primary software technology available today that closely matches the characteristics of business services. To understand the mapping from business to Web services, we need to understand the fundamental characteristics of the latter. This chapter therefore will introduce the main Web services concepts and standards. It does not intend to be a comprehensive description of all standards applicable to Web services, as many of them are still in a state of flux. It focuses instead on the more important and stable standards. All such standards are fully and precisely defined and maintained by the organizations that have defined and endorsed them, such as the World Wide Web Consortium (http://w3c. org), the OASIS organization (http://www.oasis-open.org) and others. We advise readers to visit periodically the Web sites describing the various standards to obtain the up to date versions.