tmux

terminal multiplexer
tmux enables a number of terminals (or windows) to be accessed and
controlled from a single terminal like screen. tmux runs as a
server-client system. A server is created automatically when
necessary and holds a number of sessions, each of which may have
a number of windows linked to it. Any number of clients may connect
to a session, or the server may be controlled by issuing commands
with tmux. Communication takes place through a socket, by default
placed in /var/run. Moreover tmux provides a consistent and
well-documented command interface, with the same syntax whether used
interactively, as a key binding, or from the shell. It offers a
choice of vim or emacs key layouts.