Source : Free On-Line Dictionary of Computing

X Window System
     
         A specification for
        device-independent windowing operations on {bitmap display}
        devices, developed initially by {MIT}'s Project {Athena} and
        now a {de facto standard} supported by the {X Consortium}.  X
        was named after an earlier window system called "W".  It is a
        window system called "X", not a system called "X Windows".
     
        X uses a {client-server} protocol, the {X protocol}.  The
        server is the computer or {X terminal} with the screen,
        keyboard, mouse and server program and the clients are
        {application programs}.  Clients may run on the same computer
        as the server or on a different computer, communicating over
        {Ethernet} via {TCP/IP} protocols.  This is confusing because
        {X clients} often run on what people usually think of as their
        server (e.g. a file server) but in X, it is the screen and
        keyboard etc. which is being "served out" to the applications.
     
        X is used on many {Unix} systems.  It has also been described
        as over-sized, over-featured, over-engineered and incredibly
        over-complicated.  X11R6 (version 11, release 6) was released
        in May 1994.
     
        {Home (http://www.x.org/)}.
     
        See also {Andrew project}, {PEX}, {VNC}, {XFree86}.
     
        {Usenet} newsgroups: {news:comp.windows.x}, {news:comp.x},
        {news:comp.windows.x.apps}, {news:comp.windows.x.intrinsics},
        {news:comp.windows.x.announce}, {news:comp.sources.x},
        {news:comp.windows.x.motif}, {news:comp.windows.x.pex}.
     
        (1999-04-02)