In order to leverage XML's power as a self-describing and extensible language, we need a way to define and describe the allowable content of any type of XML document. In the past, this has been achieved with DTDs, but these have in many ways fallen short of the requirements for working with data. XML Schemas were created to provide a more powerful and flexible mechanism for describing permissible document structures using XML syntax. They provide a set of built-in datatypes, which can mimic the object-oriented mechanisms of many languages, offer support for namespaces, and facilities for automated documentation. Professional XML Schemas exhaustively details the W3C XML Schema language, and teaches the new syntax in an intuitive and logical way. From declaring elements and attributes, creating complex content models, and working with multiple namespaces, you'll move on to see how XML Schemas are used in real-world situations. A number of practical case studies will illustrate the design and creation of schemas in the diverse worlds of relational databases, document management, and e-commerce applications.