Desktop environment, think KDE or Gnome.

A desktop environment. It includes most of the software you directly interact with once you boot up your computer (session manager, window manager, task bar, etc…) Some of the user friendly DEs used in Linux include GNOME (default for Ubuntu), Cinnamon (default for Mint), KDE, Xfce…

If you have no DE at all, you just have a shell and you can interact with your system only through command lines.

But in Linux, there’s a middle ground where it’s also possible to have only some of the software that make up a DE while keeping your system somewhat minimal. For example, you can login through the shell (and not use a session manager) but then run “startx” if you use X11 or a window compositor like “sway” if you use Wayland and still have a graphic session.

In computing, a desktop environment (DE) is an implementation of the desktop metaphor made of a bundle of programs running on top of a computer operating system that share a common graphical user interface (GUI), sometimes described as a graphical shell. The desktop environment was seen mostly on personal computers until the rise of mobile computing. Desktop GUIs help the user to easily access and edit files, while they usually do not provide access to all of the features found in the underlying operating system. Instead, the traditional command-line interface (CLI) is still used when full control over the operating system is required.

A desktop environment typically consists of icons, windows, toolbars, folders, wallpapers and desktop widgets (see Elements of graphical user interfaces and WIMP). A GUI might also provide drag and drop functionality and other features that make the desktop metaphor more complete. A desktop environment aims to be an intuitive way for the user to interact with the computer using concepts which are similar to those used when interacting with the physical world, such as buttons and windows.

While the term desktop environment originally described a style of user interfaces following the desktop metaphor, it has also come to describe the programs that realize the metaphor itself.[1] This usage has been popularized by projects such as the Common Desktop Environment, KDE, and GNOME.