Cinnamon began as a fork of GNOME 3 in 2011, created by the Linux Mint team.
GNOME 3 replaced GNOME 2’s traditional desktop layout with GNOME Shell, a change that dissatisfied many Mint users and developers. Linux Mint first built extensions called Mint GNOME Shell Extensions to restore familiar features such as a panel and conventional window management.
Those extensions could not provide enough long-term control, so the team forked GNOME Shell and related components. Cinnamon initially remained closely tied to GNOME technologies, but it became an independent desktop environment with Cinnamon 2.0, released in October 2013.
Cinnamon is often confused with MATE because both arose from dissatisfaction with GNOME 3. MATE, however, was forked from GNOME 2 and aimed to preserve that older desktop directly. Cinnamon instead developed from the GNOME 3 codebase while recreating a traditional desktop experience. It remains especially associated with Linux Mint.