As powerful as Cascading Style Sheets are, they aren't really dynamic per se. They give you control of how a document looks when it's first put on the screen, but what about after that?
In addition, dynamic HTML (DHTML) lets users directly interact with Web pages, so you can create far more sophisticated user interfaces than with simple HTML. For example, the Web site for Panic uses DHMTL, so users can quickly download the company's software (Figure 11.1). Clicking the application icon displays more information about the product, but dragging and dropping the same icon downloads the application. This kind of interface would not be possible without DHMTL.
Figure 11.1. On the Panic Web site (panic.com), you can click an application icon to view details about the product or drag and drop the icon to download the application.
This chapter discusses what makes DHTML dynamic and looks at how the technology compares to the other leading dynamic Web technology, Flash.