Markup: XML & related technologies

Markup enables the various parts and features of a given set of content to be distinguished and named. It provides a way to label, describe, and delimit these in a publication so that processing systems can tell them apart and know how they relate to each other. Markup languages are used to define specific markup schemes. In the past, markup languages were typically proprietary and used only by specialists. The Web gave rise to one of the simplest and most widely used markup languages ever devised, HTML, and also to one of the most flexible and powerful: XML, the Extensible Markup Language. After a brief overview of earlier markup languages, this chapter focuses on the technologies in the XML family-- XML itself, and related standards for defining, styling, linking, transforming, and annotating--that provide the foundation for digital publishing today.