This book gives an in-depth examination of the core concepts and general principles of Web application development. This book uses examples from specific technologies (e.g., servlet API or XSL), without promoting or endorsing particular platforms or APIs. Such knowledge is critical when designing and debugging complex systems. This conceptual understanding makes it easier to learn new APIs that arise in the rapidly changing Internet environment. It includes discussions of markup languages such as: HTML, the eXtensible Markup Language (XML), XHTML, eXtensible Stylesheet Language (XSL), and Cascading Style Sheets (CSS). It contains exercises geared to constructing an advanced XML application that makes use of XML and XSL parsers. It explores emerging technologies such as: Java 2 Enterprise Edition (J2EE), industry-specific XML standards, Resource Description Framework (RDF), and XML query languages.