Screen is a text window manager. It allows you to open several virtual windows from one text console. You can easily switch between windows using keyboard commands. One of the strongest feature of screen is decoupling the virtual windows from the console. In simple terms, you can leave a program running in a virtual window and log off and then re-attach to the same session later. Here is how you do it.

After logging into the machine, run type in command "screen". Screen will present the license, hit enter to continue. After this the first virtual window has been created and you can run your program. To navigate the session use the following key combinations:

1. To create a new virtual window and switch to it - ^ac
2. To switch to previous window - ^ap
3. To switch to next window - ^an
4. To see a list of windows - ^a"
5. To see a list of available commands - ^a?
6. To detach from windows - ^ad
7. To re-attach to previous session type "screen -r".

^ means hold down control key and then type the commands.

These are a few frequently used commands. A more detailed tutorial is here.