CSS allows you to set up elements called “layers” on the screen that can be absolutely positioned in relation to the Web page. For example, you can set up a layer containing graphics, text, forms, or any other HTML elements and then position that layer 25 pixels from the top of the page and 360 pixels over. This layer will ignore all other content on the page even if it overlaps the content that is underneath it.
Dreamweaver refers to these CSS positioned layers as Draw Layers and provides special tools, not only to add and move these layers, but also to allow you to animate these layers, show and hide them, change their size, or even allow the visitor to move them around in the browser window.
Because draw layers can work as free agents in the page, this not only opens a lot of possibilities for layout, but can be used to add a bit of dynamic zest to your page. You can place the draw layers around the page for the exact positioning you need in your design, crop parts of a layer to create independently scrollable regions, or even hide draw layers and then use Dreamweaver behaviors to show them when needed.