What Are Web Services?

"A Web service is a software application identified by a URI, whose interface and bindings are capable of being identified, described and discovered by XML artifacts and supports direct interactions with other software applications using XML based messages via Internet-based protocols."

(World Wide Web Consortium)

A Web service is simply an application that exposes a function that is accessible using standard Web technology and that adheres to Web services standards. This is significant because Web services are developed for and deployed onto any platform using any programming language. There is nothing revolutionary or exceptional about the technology of Web services. The technology is simple. In fact, you use and probably have developed applications already that incorporate most of the technologies of Web services.