What is screen session?

Screen or GNU Screen is a terminal multiplexer. In other words, it means that you can start a screen session and then open any number of windows (virtual terminals) inside that session. Processes running in Screen will continue to run when their window is not visible even if you get disconnected.

What does screen do in Linux?

Simply put, screen is a full-screen window manager that multiplexes a physical terminal between several processes. When you call the screen command, it creates a single window where you can work as normal. You can open as many screens as you need, switch between them, detach them, list them, and reconnect to them.