X - a portable, network-transparent window system

The X Window System is a network transparent window system which
runs on a wide range of computing and graphics machines. It should
be relatively straightforward to build the X.Org Foundation software
distribution on most ANSI C and POSIX compliant systems. Commercial
implementations are also available for a wide range of platforms.

The X.Org Foundation requests that the following names be used when
referring to this software:
	           X
    	    X Window System
	      X Version 11
       X Window System, Version 11
	          X11

X Window System is a trademark of The Open Group.
   
WWW: http://www.X.org