DisplayServer

A display server is software that provides a display server protocol and coordinates graphical output and input for client applications. It mediates between applications and the graphics hardware, handling rendering, surface compositing, input events, and, in some systems, authentication and security.

Historically, the X Window System (X11) used a separate X server as the display server, managing windows and input for X clients. More recently, Wayland reinterprets the role: the display server is essentially a compositor that renders and composites surfaces, with clients drawing to buffers that the compositor displays. Weston is the reference Wayland compositor; other examples include Sway, KWin, and GNOME Shell's Mutter/Wayland sessions.

Architecturally, a display server interacts with input devices (keyboard, mouse, touch) via input libraries (such as libinput) and with display hardware via graphics drivers and modesetting, typically through DRM/KMS. In Wayland, clients render content to buffers and the compositor composes these buffers into the final frame; in X, the server receives drawing commands from clients and uses the server to render windows.

Display servers are part of the broader graphics stack used on Linux and other Unix-like systems; they are distinct from display managers, which handle user login and session startup. While X11 historically supported network transparency, modern display servers like Wayland focus on performance and security for local graphical sessions, with compatibility layers (e.g., XWayland) enabling legacy X clients.