The Cinnamon desktop environment is a free and open-source graphical user interface (GUI) for Linux-based operating systems. It's known for its user-friendly and visually appealing design, making it a popular choice among Linux enthusiasts and users looking for a more traditional desktop experience.

Key features of the Cinnamon desktop environment include:

1. Start Menu: Cinnamon provides a classic start menu, similar to what you might find in Windows. It allows users to access applications, settings, and system functionalities easily.

2. Taskbar and System Tray: Cinnamon has a taskbar at the bottom of the screen, where you can manage open applications, switch between virtual desktops, and access the system tray for notifications and quick settings.

3. Window Management: It offers advanced window management features, including window snapping, tiling, and window grouping.

4. Customization: Cinnamon is highly customizable. Users can change the desktop wallpaper, themes, icons, and other aspects of the desktop's appearance and behavior.

5. Applets: Cinnamon supports applets, which are small, customizable widgets that can be added to the desktop or the panel to provide quick access to various functions and information.

6. Workspace Management: It allows users to create and manage multiple workspaces (virtual desktops), which is helpful for organizing and multitasking.

7. Cinnamon Spices: Cinnamon has a system called "Cinnamon Spices" that allows users to easily install and manage extensions, applets, themes, and desklets to further customize their desktop experience.

Cinnamon was originally developed for the Linux Mint distribution but can be installed on various other Linux distributions as well. It is built using the GTK (GIMP Toolkit) and Mutter, which are common libraries in the Linux desktop ecosystem. Cinnamon aims to strike a balance between modern features and a traditional desktop layout, making it a popular choice for users who prefer a more classic desktop environment.