X Window System

The X Window System (sometimes called X11 or just X) is the now-dominant window system used by applications which wish to perform output to a window (either in the form of text, graphics, or images).

Unlike earlier window systems, which were part of an operating system, or interacted though subroutine calls, X is based on a protocol which runs over a reliable byte stream. An X session can be run over any data network which provides such streams. (Currently TCP/IP internets are used, but in the past the CHAOS protocol was also used.) The streams connect the application to an X server which has direct access to the display being used.

X is based on the W window system (which was used initially for a window system in the CLU project)), but Bob Scheifler largely re-wrote it to become X.

External links

• The X Window System, Robert W. Scheifler, Jim Gettys (ACM Transactions on Graphics 5 (2), April 1986)
• The X Window System, Robert W. Scheifler, Jim Gettys (TR-368,MIT-LCS)
• X version history, prehistory