Overview Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells.
All windows run their programs completely independent of each other.
Programs continue to run when their window is currently not visible and even when the whole screen session is detached from the users terminal. Everything you type is sent to the program running in the current window. The only exception to this is the one keystroke that is used to initiate a command to the window manager. The standard way to create a new window is to type C-a c . This creates a new window running a shell and switches to that window immediately, regardless of the state of the process running in the current window.