It became the default window manager in GNOME 3, replacing Metacity[4] which used GTK for rendering.

Mutter can function as a standalone window manager for GNOME-like desktops, and serves as the primary window manager for the GNOME Shell,[5] which is an integral part of GNOME 3.

Mutter is extensible with plug-ins, and supports numerous visual effects.

GNOME Shell is written as a plug-in to Mutter.

Muffin is a fork of Mutter by the Linux Mint team for their Cinnamon desktop environment.