GUI
Graphical User Interface - a visual way to interact with a computer using windows, icons, menus, and a mouse pointer.
A GUI (Graphical User Interface) is a type of user interface that allows people to interact with a computer through visual elements such as windows, icons, buttons, menus, and a mouse pointer, rather than typing text commands. On Linux, the graphical environment is built on a display server protocol, historically X11 (X Window System) and increasingly Wayland. Desktop environments like GNOME, KDE Plasma, XFCE, and Cinnamon provide complete GUI experiences including file managers, settings panels, application launchers, and window management. The GUI layer on Linux is entirely separate from the underlying operating system, meaning users can choose different desktop environments, switch between them, or opt to run a system without a GUI at all (common on servers). This separation and flexibility is a distinctive feature of Linux compared to Windows and macOS.