Web services are open standard (XML, SOAP, HTTP etc.) based Web applications that interact with other web applications for the purpose of exchanging data.
Web Services can convert your existing applications into Web-applications.
In this tutorial you will learn what exactly Web Services are and Why and How to use them.
This tutorial will be useful for all those readers inclined to learn the basics of web services and implement them in practice.
This is an elementary tutorial that introduces the concepts of web services. It does not require the readers to have a prior knowledge of any technology in particular, however it would certainly make you comfortable if you have a basic understanding of XML, HTTP, TCP/IP concepts.