This document provides an introduction to web services, including the key specifications that form the basis of web service technology: SOAP, WSDL, and UDDI. SOAP defines an XML format for messages, WSDL provides a standard way to describe web services and their operations, and UDDI allows services to be published and discovered. The document explains the basic structures and components of SOAP messages, WSDL documents, and how frameworks like Axis2 can be used to develop web services using either a contract-first or code-first approach.