X Window System

X Window System, simply called 'X' or 'X11', is a technology enabling graphical data to be displayed over heterogeneous platforms.

The X Window System is not an off-the-shelf product such as Microsoft Windows, but a set of standard conventions and tools for creating networked windowing environment. It is technically a graphical windowing architecture formed with graphic protocol, network protocol, and application interface.

From the design point of view, the X Window System is made up of X client, X server, and X protocol that defines the exchange of information between server and client. X server is running on the local computer while X client is running on the remote computer, and X client can be connected to X server anytime through network connection.

X Window System Overview
X Server - Graphic operating system(Window Base System)
  • makes and manages windows.
  • sends the user input to X client.
  • draws the graphics requested by X client.
  • manages all the fonts.
X Client - X application
  • requests all the tasks related to graphics.
  • acts appropriately to the user input sent from X server.
  • processes all the tasks except graphics and input/output operations.

X is currently in its 11th revision and has been designed to be machine independent, portable, network transparent, and extensible. Although other windowing systems exist and offer similar capabilities, the attractiveness of X Window is rooted in the fact that it is not controlled or influenced by any one specific vendor.

One of the founding philosophies behind the X Window System was to lower the cost of individual seats coupled with the X Window client/server architecture. The new generation of display devices has emerged with X Window terminals and X PCs (PCs equipped with X server software emulating terminals). Using the X displays provides the solution allowing access to server-based applications by a broad range of users at lower cost than using workstations.

Because X Window is not specific to any network topology, hardware device, or operating system, it currently runs not only on various Unix-based machines but also on MS Windows PC platforms using the PC X server software package such as Xmanager.