"The best way to learn screen is to try it yourself, so
open a console, type screen, and then press Enter. Your display
will blank momentarily and then be replaced with a console; it will
look like nothing has changed. Now, let's do something with that
terminal. Run top and leave it running for the time being. Hold
down the Ctrl key and press a (referred to as Ctrl+a from now on);
then let go of them both and press c. Your prompt will clear again,
leaving you able to type. Run the uptime command."