GNOME is a desktop environment which is used in Linux distributions like Ubuntu and Fedora, because GNOME share the same vision as these distributions. And one of these goals are simplicity and ease of use.
What differentiates GNOME 3 from other GNOME desktop environments, such as KDE and Xfce, is that it has three menus instead of one. GNOME has one menu for applications, one for places (hard disks, CD-ROM, network locations etc.) and a configuration tool.