tmux is a terminal multiplexer that lets you switch easily between several programs in one terminal, detach them (they keep running in the background) and reattach them to a different terminal, and a lot more.
- The tmux manpage (man tmux) or the printed copy of the tmux book near the team's library are great resources on using tmux.
This HOWTO just lists the most useful commands. - Despite tmux being a very powerful tool, the default configuration of tmux is not the most user friendly.
I am maintaining a tmux configuration file that makes life a bit easier here:
https://github.com/kmhofmann/dotfiles
The HOWTO is written assuming this configuration file (or one with similar mappings) is installed.