By default, Ubuntu comes with its own modified GNOME desktop environment that resembles the look and feel of Canonical’s deprecated Unity interface. This is called the Ubuntu session or simply ???Ubuntu??? when you select the session from the login screen. Now, there’s nothing wrong with the Ubuntu session. In fact, I actually like it very much as of lately. But if I want to use the vanilla GNOME session to experience the real GNOME desktop environment and make my own changes to it, I have to install some packages.