Editing Windowing system (section)

===X11===
{{Main|X Window System core protocol|X Window System}}

[[File:X11 display server protocol.svg|thumb|350px|The [[X.Org Server]] communicates with its clients, e.g. [[Amarok (software)|Amarok]], over the X11 protocol.]]
{{stack|[[File:X11.svg|right|60px|X Window System logo]]}}

One example of a display server is the [[X.Org Server]], which runs on top of the kernel (usually a [[Unix]]-like kernel, such as [[Linux]] or [[BSD]]). It receives user input data (e.g. from [[evdev]] on Linux) and passes it to one of its clients. The display server also receives data from its clients; it processes the data, it does the compositing and on Linux it passes the data to one of three kernel components &ndash; [[Direct Rendering Manager|DRM]], [[Graphics Execution Manager|gem]] or [[KMS driver]]. The component writes the data into the [[framebuffer]] and content of the framebuffer is transmitted to the connected screen and displayed. X relies on [[GLX]].

One of the implementations of display server concept is [[X Window System]], in particular its actually used version &ndash; [[X.Org Server]] and [[Xlib]] and [[XCB]] client libraries. The X.Org Server is a display server, but in its current implementation it relies on a second program, the [[compositing window manager]], to do the compositing. Examples are [[Mutter (window manager)|Mutter]] or [[KWin]].

Notable examples of display servers implementing the X11 display server protocol are [[X.Org Server]], [[XFree86]], [[XQuartz]] and [[Cygwin/X]], while client libraries implementing the X11 display server protocol are [[Xlib]] and [[XCB]].