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The X Window System, or "X" as it is sometimes called, can be thought of as a terminal for UNIX environments with a graphical user interface. X was developed in the early 1990s as a basic client/server system, except that the terminology is reversed from the way people think of client/server today. In a typical X Window arrangement, the user's terminal only displays information and accepts keyboard input. Both the client and server processing is executed at a remote device. Since the remote device (and not the user's terminal) runs the client software, it is called the X client. Since the user's terminal "serves up" the screen information, it is called the X server. X provides an environment for developing graphical client/server applications, and a developer can use a GUI development toolkit such as Motif to create the applications. See "Motif" for more information.

X provides a common windowing system that bridges many platforms. It is the standard graphical engine for UNIX and Linux. X is inherently independent from operating systems and hardware. Many applications are available that integrate X applications to network computers or personal computer environments such as Windows.

X can be used to create and access interactive applications on the Web. The browsers can invoke remote applications, and its integration with HTTP protocols makes access to applications platform independent, allowing "universal access" to any application. Optimization techniques are used to improve performance over WANs and serial lines by using caching, compression, and other techniques.

An interesting aspect of X is that it is the model for "thin clients," small-footprint computers that run Java applications, relying heavily on centralized servers to do much of the work.

The latest version of The X Window System is System 11 Release 6.x (as of this writing, the exact version was release 6.5.1, but further upgrades may occur by the time you read this).

Two Internet RFC provide information about the X Window System:

• RFC 1198 (FYI on the X Window System, January 1991)


• RFC 1013 (X Window System Protocol, Version 11, June 1987)

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.