Chapter 1. Essential XML

Welcome to the world of Extensible Markup Language (XML). This book is your guided tour to that world, so have no worries—you've come to the right place. The world of XML is large and is expanding in unpredictable ways every minute, but we'll become familiar with the lay of the land in detail here. We also have a lot of territory to cover because XML is getting into the most amazing places, and in the most amazing ways, these days.

XML is a language defined by the World Wide Web Consortium (W3C, at http://www.w3c.org), the body that sets the standards for the Web. This first chapter is all about getting a solid overview of that language and how you can use it. For example, you probably already know that you can use XML to create your own elements by designing a customized markup language for your own use. In this way, XML supercedes other markup languages such as Hypertext Markup Language (HTML): In HTML, all the HTML elements you can use are predefined—and there are simply not enough of them. In fact, XML is a meta-markup language because it lets you create your own markup language.