XSLT and XPATH: A Guide to XML Transformations

1.1. What Is Markup?

Without retelling the story of how markup evolved or what it is, it is important to begin with a conceptual understanding of XML. This book is not intended to provide an explanation of the complete syntax and usage of XML, however, there are a few concepts that are worth reviewing. XML is a markup language that is a derivation—or flavor—of SGML (Standard Generalized Markup Language). You may be more familiar with HTML, a popular example of SGML that is used to mark up content for presentation on the Web.

Markup is made up of tags, which describe and separate the contents of an XML document instance from the presentation, style, and format of the document. The tags can be thought of as hooks, or handles, by which all material ...