Which display protocol is intended to replace the X Window System in Linux? The answer is Wayland. It is a modern display protocol designed as a prospective replacement for X11, the protocol traditionally used by the X Window System on Linux and other Unix-like systems.
Wayland began in 2008, initially through work by Red Hat developer Kristian Høgsberg. Unlike X11’s architecture, Wayland places a compositor at the center of the display session. The compositor handles responsibilities such as presenting windows, compositing frames, and coordinating input, while clients render their own surfaces.
Wayland is a protocol rather than a complete desktop environment. Weston is its reference compositor, while Mutter and KWin provide Wayland sessions for GNOME and KDE Plasma. XWayland supplies compatibility for older X11 applications, so users can run legacy software during the transition. Mir and DirectFB were also proposed as alternatives in different contexts, but Wayland is the canonical successor named by this question.