GNU Screen can be thought of as a text version of graphical window managers, or as a way of putting virtual terminals into any login session. It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively.

Persistence

Similar to VNC, GNU Screen allows the user to start applications from one computer, and then reconnect from a different computer and continue using the same application without having to restart it. This makes migration between locations like work and home simple. Screen provides terminal-agnostic functionality so that users can disconnect and reconnect using different terminal types, allowing applications to continue running without being aware of the change in terminals.

Multiple windows

Multiple terminal sessions can be created, each of which usually runs a single application. The windows are numbered, and the user can use the keyboard to switch between them. Some GUI terminal emulators provide tabs or otherwise similar functionality to this. Each window has its own scroll-back buffer, so that output is captured even when the window isn't actively displayed, and that history can be saved even when migrating to another computer. Windows can be split-screened. While some text applications have this functionality built in, Screen allows any application to be split-screened alongside any number of other applications.

Session Sharing

Screen allows multiple computers to connect to the same session at once, allowing collaboration between multiple users. The same computer can also be used to make multiple simultaneous connections, providing alternative functionality to screen-splitting, particularly for computers with multiple monitors.