X

The X Window System (X11) is the foundational, network-transparent display protocol for building graphical user interfaces (GUIs) on Unix-like operating systems.

X11 operates on a robust client-server model: the X server manages the display and input (mouse, keyboard), while X clients (applications) request rendering operations. This architecture enables network transparency, meaning an application can run on a remote server (e.g., a Linux machine) and display its GUI directly on a local workstation. Developed at MIT in 1984, the current protocol version, X11, has been the standard since 1987. The X.Org Foundation now stewards the open-source reference implementation, X.Org Server, which is the core component for most Linux and BSD desktop environments (like GNOME and KDE).

https://www.x.org