X Window System
![A historical example of graphical user interface and applications common to the MIT X Consortium's distribution running under the twm window manager: X Terminal, Xbiff, xload and a graphical manual page browser](/Images/godic/202502/21/X-Window-System1142.png")
![A modern example of a graphical user interface using X11 and KDE.](/Images/godic/202502/21/Screenshot_of_KDE.1143.png")
![Simple example: the X server receives input from a local keyboard and mouse and displays to a screen. A web browser and a terminal emulator run on the user's workstation and a terminal emulator runs on a remote computer but is controlled and monitored from the user's machine](/Images/godic/202502/21/X_client_server_example.svg1143.png")
![GNOME graphical user interface](/Images/godic/202502/21/GNOME_Shell1143.png")
The X Window System (X11, or shortened to simply X, and sometimes informally X-Windows) is a windowing system for bitmap displays, common on UNIX-like computer operating systems.
X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting with a mouse and keyboard. X does not mandate the user interface — this is handled by individual programs. As such, the visual styling of X-based environments varies greatly; different programs may present radically different interfaces.