Web service support is one of the most significant advances in the .NET architecture. The .NET Framework supports both creating and consuming Web services through command-line tools as well as the Visual Studio .NET IDE.
Web services provide a way to invoke objects over the Internet. A Web service can expose one or more Web methods, each of which can accept parameters and return objects.
Web services use protocols and standards, including SOAP, Disco, UDDI, and WSDL to communicate. These protocols and standards are designed to use HTTP as their transmission mechanism so that they are generally not blocked by firewalls.
The .NET Framework includes command-line tools to aid in the discovery and use of Web services. Visual Studio .NET enables you to easily use these tools in the simple act of setting a Web reference. Either of these methods produces local proxy classes that you can use to send messages to a Web service and that will return the results from the Web service to the rest of the application.