It's easy to take the terminal for granted. After all, modern terminal emulators like gnome-terminal, konsole, and the others included with Linux desktop environments are feature-rich applications that satisfy most of our needs. But sometimes we need more. We need to have multiple shell sessions running in a single terminal. We need to display more than one application in a single terminal. We need to move a running terminal session from one computer to another. In short, we need a terminal multiplexer.
Terminal multiplexers are programs that can perform these amazing feats. In this adventure, we will look at three examples: GNU screen, tmux, and byobu.
Source: Linux Command Line Adventure: Terminal Multiplexers an article by William E. Shotts, Jr.