Dreamweaver 8

Angie,

'Layer' can mean more than one thing.

If you're talking about CSS layouts, there are 'div' tags all over the place. 'Layers' (boxes that you can move around on the screen) are also DIV tags but often given absolute positioning (so sometimes known as AP elements).

(Also, a 'layer' in a graphics program eg. photoshop, is a different thing again).

You would use Layers (AP elements) if you wanted to place an element at an exact location on your page.
You would also use Layers if you wanted to move -or allow your visitor to move- content around on the page.
You could use layers to create a show/hide type interface (setting the layer visibility on and off).

See also:
http://www.teacherclick.com/dreamweaver8/t_12_1.htm
http://www.entheosweb.com/dreamweaver/layers.asp

Regards, Rich