Tags are used in HTML5 to place and organize content at a level that is descriptive. This does not mean that the page will look good. Presentation of content on the page is controlled using Cascading Style Sheets Level 3, or CSS3, in HTML5.

Using CSS3 to describe how your page should look, however, is not new. The technology was first introduced in 1997 and is now, in HTML5, in its third major release, named CSS3. The good news is that all CSS1 and CSS2 standards are fully supported by popular web browsers.

For this book you will use CSS to format web pages. There are good reasons why you want to do this. The first, and most important, is that CSS is a tool that allows you to easily apply page styling techniques to a whole web site from a single, text-based document. This means you can quickly change the visual layout of a page, selection of pages, or the entire site.