XML

If you have read much -about the Web recently, you have undoubtedly heard about XML. XML, or Extensible Markup Language, which has been widely touted as the most exciting new development in Web technology. This book on XML gives you a thorough grounding into what XML is and the different processes you need to master, to create an XML application. This book assumes that you have a basic understanding of the Web and familiarity with HTML. In this chapter, we will introduce you to the basics of markup language, the development of XML right from GML onwards and a simple XML program.

Before you can f ully understand what XML is and why it was developed, it's helpful to understand where it came from. Quite simply, markup refers to anything put on a document which adds special meaning to or provides extra information about that document. For example, a highlighted text is a markup. But unless others understand our markup, it is of little use, so we need a set of rules encompassing the following two points for it to be understood:

1. To declare what constitutes a markup.
2. To declare exactly what our markup means,

A markup language refers to a set of rules. In the late 1960s, three researchers at IBM, Charles Goldfarb, Ed Mosher and Ray Lorie created a system of document formatting and named it as Generalized Markup Language (GML). GML was created, .when the researchers were working on the global problem of dealing with thousands of legal documents created on disparate systems that used proprietary formats.

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