I write here a very concise guide to linux screen (ok, I assume you know something about linux, even if you are a biologist…).
It takes five minutes to learn and you can live with it for all of your life. Trust me, I’m a biologist!

Why screen?
If you work on a remote server and there is an interruption of your internet/LAN connection, all you were doing is gone. Screen prevents you against these data losses.
How does it work?
Simple. To create a screen or resume an existing screen you can use the ever useful command
screen -dR

Then, when you are in screen you can do all your work ignoring you are in screen except that you have a series of screen commands that help you create several screens inside the same terminal and also move around them.
Any screen command starts pressing at the same time ctrl-a (yes, even in mac).
AFTER pressing ctrl-a you can press one of the following letters:
c: create an additional screen
n: move to next screen (if existing)
p: move to previous screen (if existing)
d: detach screen

The only command that needs not be preceded by ctrl-a is exit. If you type exit inside screen you will quite screen and erase it from memory (so do not type exit if you have unsaved work).