I am just now, ever so slowly, discovering how to use tmux. For reference via Wikipedia:
tmux is an open-source terminal multiplexer for Unix-like operating systems. It allows multiple terminal sessions to be accessed simultaneously in a single window. It is useful for running more than one command-line program at the same time.
Only been able to get the two panes working so far, barely scratching the surface of sessions in the background, but even that has been useful. Before I opted for opening tabs for each terminal session. I wonder if that springs from tabs being the defacto way I explore my computer, particularly the web. Didn't know anything else, so why not extend that approach to terminals? Tmux adds this other dimension.
Interestingly enough, tmux gives more context to the experiments I've seen with bringing panes to the web — there's a feature that's in Beaker Browser that does just thaat — here's a beta announcement that explains it. It also makes me think how TabsFS could actually bring panes to using the web by virtue of, well, bringing browser tabs to the terminal itself.
Curious to see what else is out there.