CSS doesn't really do anything by itself. To take effect, it needs to be mated with a markup language such as HTML, XHTML, or XML. A markup language is a system of instructions that are incorporated into a document that direct how the content is to be presented. HTML, XHTML, and XML are all based on SGML (Standard Generalized Markup Language), which is generally used in the desktop publishing world to markup computer documents for printing.
Because the vast majority of Web publishers use HTML to code Web pages, and are likely to do so far into the future, this book primarily deals with using CSS with HTML documents. CSS can also be used with XHTML documents.
In most cases, the examples and material provided in this book ...