Xorg for X11 display soon to be replaced in Ubuntu at least by Wayland
Running More than one Desktop Manager at a time
X Window Managers
Introduction
Compiz Fusion - a Tutorial
Introduction
What is Compiz Fusion? Compiz Fusion is a compositing window manager. What does that mean? Previously, each program you run draws graphics directly onto the screen within its own window. Compositing puts a layer in between programs and the screen, changing the flow from programs, to the intermediate buffer, to the screen. What this allows for is that graphics from a running program can be manipulated before being drawn in various 2D and 3D ways, like this:
