X Windows allows the local display of graphics from a program running remotely on another machine
if the remote machine is given permission to display locally. The easiest way to do this is to use
the ssh program with the -Y option for remote access (see Section 3.5.3).
[alice@onyx]: ssh -Y server.timbuktu.edu
--->now you are on timbuktu
$ xclock
--> the graphical clock shows up on the screen on your local computer
