Linux is a multiuser and multitasking system. The advantages of these features can be appreciated, even on a stand-alone PC system. In text mode, there are six virtual consoles available. Switch between them using Alt-F1 to Alt-F6. The seventh console is reserved for X11. More or fewer consoles can be assigned by modifying the file /etc/inittab.
To switch to a console from X11 without leaving X11, use Ctrl-Alt-F1 to Ctrl-Alt-F6. The key Alt-F7 then returns to X11.