Linux User Interfaces
When using a Linux system, you either interact with a command line or with a graphical user interfaces. Both ways grant you access to numerous applications that support performing almost any task with the computer.
Desktop environments:
GNOME: Used as the default desktop of many distributions (i.e. Ubuntu). It tries to facilitate as much as possible the system's use. It also uses GTK libraries, written in the C language.
KDE: Traditionally used by more advanced users because it offers more personalization options. It uses Qt libraries, written in the C++ language.