I have been a long time screen user when connecting to remote machines where I don’t want to lose work if the connection drops. I started using tmux and have been won over by it’s split screen feature.
To start tmux just run tmux and it will start and give you a nice status bar at the bottom. You can list out your tmux sessions with the command tmux ls, and then reattach to your session with tmux attach and the session number.
By far my favorite use for tmux is split screen so I can view multiple process outputs on the same server without opening another ssh window. tmux uses ctrl-b for it’s commands. ctrl-b “ will split the window horizontally, and ctrl-b % will split the window vertically. You can then use ctrl-b o to move between window panes.
The tmux manual has got to be one of the largest man pages ever, it can do much much more too.