This post is about display servers and windowing systems compatible with Linux, that provide graphical user interfaces.
List of Linux Display Servers
X11, also known as X Window System, is a display server for Unix-like operating systems.
Programmers at Massachusetts Institute of Technology (MIT) started developing X in 1984.
X11 is distributed under an MIT license since 1986.
Wayland is a protocol that specifies the communication between a display server and its clients.
A display server using the Wayland protocol is called Wayland compositor.
There are Wayland compositors like Mir (originally developed by Canonical), Mutter (part of the GNOME shell) or Sway
Wayland became the default display server with the release of Ubuntu 21.04 in April 2021.