gdm: gdm (the Gnome Display Manager)
gdm: 
gdm: GDM is the little program that runs in the background, runs your X
gdm: sessions, presents you with a login box and then tells you to bug off
gdm: because you forgot your password. It does pretty much everything that
gdm: you would want to use xdm for, but does not involve as much crack. It
gdm: does not use any code from xdm, and has a more paranoid and safer
gdm: design overall. It also includes many features over xdm, the biggest
gdm: one of which is that it is more user friendly, even if your X setup
gdm: is failing. The goal is that users should never, ever have to use the
gdm: command line to customize or troubleshoot GDM.