IN THIS CHAPTER
Working with Document Type Definitions
Introducing XML Schemas
Working with Schemas
Extensible Markup Language (XML) is a popular scheme for representing data. Although created as a more portable version of Standard Generalized Markup Language (SGML), XML lives mostly on the application side of the computer world. XML is used to store preferences and data from applications, provide a unified data structure for transferring data, encapsulate syndicated feeds from websites, and more. XML standards are being adopted by other data formats such as HTML (creating XHTML).
This chapter presents a primer on XML, including its format, methods, and tools.
Full coverage of XML can occupy an entire book on its own, and is therefore outside the scope of this one. In the case of the Web, XML is a bystander technology, useful to know but not entirely critical for publishing on the Web. However, because XHTML is XML-compliant, coverage is mandatory. If you desire more information about XML, you can pick up a book dedicated to the subject, such as WROX Beginning XML, Third Edition, WROX XSLT 2.0 Programmer's Reference, Third Edition, or Wiley's XML Weekend Crash Course or XML Programming Bible.
XML was created to bring the advantages of the SGML standard to smaller platforms such as Web browsers. XML retains the flexibility of its older sibling but has been redesigned for the Web, enabling it to be easily transmitted ...