XML Web Services provide a simple technique for accessing a
method on an object that is running on a local or remote computer. Web
Services can be accessed by an application written in any language and running
on any operating system. They utilize HTTP as the underlying transport, which
allows function requests to pass through corporate firewalls (as they move
through port 80). In ASP.NET we can write a Web Service as simple as a normal
business object and the only difference is that the functions are preceded with
a special <WebMethod ()>attribute that makes them as Web Services. Typical
implementation of Web Services might include shipment tracking, credit card
verification, searching for airfare rates, Weather forecasting, etc.