Visual Effects - exactly what are they?

[vonskippy]

I've searched, and find many topics (both here and on Ubuntu forums) about problems with getting Visual Effects to work, or problems with stability, etc., but I can find anything that clearly describes what the various Visual Effects do?

So, what exactly does "none", "normal", and "extra" do?

What effects do they add, how (as in what mouse/keyboard commands) are they used, etc.

I have a system set to "normal" - and it seems like the mouse wheel will scroll between desktops, and putting the mouse into the system tray (or whatever you call where the clock is) seems to display all of the open windows in transparent mode so that you can pick which one to go to. Am I missing any?

[Husse]

With "extra" you get the cube and wobbling windows and a lot of other Compiz stuff which you don't get in the other settings
You need to have a working 3D driver (and card) for this to work