What is the difference between graphical environment, user interface, graphical shell and a windowing system? How they cooperate and how are they built on top of each other? For example, from en.wikipedia, I've read that

Unity (user interface)
Unity is a graphical shell for the GNOME desktop environment



GNOME Shell is the graphical shell of the GNOME desktop environment

1 Answer 1


Basically, without going too much into detail:

The User Interface (UI) is a generic term for the space where interactions between user and computer occur. Mainly, you're talking here about a Graphical User Interfaces (GUI).

The desktop environment is a GUI which is an implementation of the desktop metaphor and allows users to interact with an operating system. GNOME and KDE are examples of Linux desktop environments.

The graphical shell is the core of a specific desktop environment and allows the user to do basic tasks such as launching a program or searching for files.

  • Hey, thanks for the great explanation. I have one last question, if you want: where the windowing system inserts in all of these?
    – tigerjack
    Apr 24, 2015 at 15:06
  • The windowing system (X Window System aka X11 in Linux) defines a set of graphic primitives to display windows in a GUI. The desktop environment is built on top of that. P.S.: If this answer suits you please consider marking it as Accepted Answer.
    – dr_
    Apr 24, 2015 at 15:16
  • So, in a generic Linux System, the lowest level is the X11 System, on top of it there is the DE (like GNOME or KDE), on top of them (?) there is the UI. Am I right?
    – tigerjack
    Apr 24, 2015 at 15:20
  • Well, you could consider X11 the lowest level of the GUI in Linux. On top of that there's the desktop environment. On top of the desktop environment, the graphical shell and the graphical applications. All these components make up the GUI.
    – dr_
    Apr 24, 2015 at 15:28
  • Thanks again. So, when in Ubuntu, for example, I'm switching between Unity and GNOME 3, what I'm really changing and what I'm preserving?
    – tigerjack
    Apr 24, 2015 at 15:43

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