Screen is a neat little program that allows you to use multiple virtual terminals in a single session on Unix/Linux and Mac. However, it does more than just that. It can also allow you to share your current session on a machine with another user - allowing you to collaboratively hack away at a problem in real time.
My book Create Simple GUI Applications with Python & Qt5 has been updated! New chapters on multithreading and packaging your apps.
GNU Screen is a command-line application that allows use of multiple virtual sessions within a single real terminal or remote session. Importantly, it allows for persistent running of command-line applications independent of the shell that initiated them program, meaning active applications can persist during disconnection.