The Code panel has two different applications. The first is the snippets tab. This Panel allows you to create small bits of HTML or other code, and then re-use them quickly throughout your site. Dreamweaver also comes with many pre-defined snippets that will get you started quickly.
The second tab of the code window is the Reference tab. This is where you go if you need to look up an HTML tag. There are many reference manuals included from various sites, such as O'Reilly and Wrox press.
