Windows Key + a lower case L = a locked computer. This command is essential. It locks your screen so that your computer cannot be used until you put in a password (if it’s password protected) or until you “wake” the computer by moving the mouse (if it’s not password protected).
This command makes it so you can walk away from your computer, even while you have work in progress, and know that it’s secure. When you log back in, you will see the screen that you were working on when you locked the computer.
The only trick to remember is to hold both the Windows key and thelower case L down at the same time. It’s that simple.