Screen
Ctrl a c -> Creates a new screen session so that you can use more than one screen session at once.
Ctrl a n -> Switches to the next screen session (if you use more than one).
Ctrl a p -> Switches to the previous screen session (if you use more than one).
Ctrl a d -> Detaches a screen session (without killing the processes in it - they continue).
screen -ls  -> See all screens