GNOME Shell is an open source application that is distributed as part of the GNOME project. It offers a modern and attractive user interface on top of the GNOME desktop environment. Actually, we can’t really call it an application. We believe that the right term for this piece of software is “a component of the GNOME desktop environment.”
It's in charge of everything you do in GNOME
It is in charge of everything you do on your GNOME desktop, from launching applications, searching files and apps on your computer, to switching workspaces and managing your system’s brightness, session, battery, and Internet connection. GNOME Shell is also in charge of the visual effects that you see on your GNOME desktop, the panel, the system notifications, and for the way you interact with your desktop.
You can view all your running apps
An interesting feature is the ability to view all your running application, a function that is called overview mode. However, one should not confuse the overview mode with the Alt-Tab Task Switcher function, which is still available.
Under the hood
Under the hood, the program acts as a compositing manager for the GNOME desktop environment, displaying application windows and various other UI (User Interface) objects. In order words, if GNOME Shell crashes, there will be no way to interact with your system. One should install the entire GNOME desktop environment and use the GNOME Shell session in order to enjoy its features.
GNOME Shell is not part of the GNOME Classic session, which provides an old-style, two-panel desktop for nostalgics. Of course, this means that there’s no other way for a Linux user to test the GNOME Shell software on their operating systems, as it depends on many other GNOME components and libraries.
All in all, we strongly recommend to install the GNOME desktop environment with the GNOME Shell user interface, if you want to enjoy a modern and eye-candy desktop experience.