Consider the problem of “how do I run more than 1 terminal at a time”. At this moment, I have at least 5 different ways I can effectively solve this issue: I can, from a different physical computer, SSH in to a new session. I can, from the same physical computer, switch to a different tty session with … C-S-F2 through 6 or something. (Rare, but sometimes it comes in really handy....
Between our ESP32 prokaryotic organisms and our 24/7 Internet-enabled megafauna servers, there exists a vast and loosely-defined ecosystem of things the B2B world likes to call computer appliances. Picture a bespoke Pi 4 packaged up neatly with some Python scripts, a little fancy plastic embossing, and maybe a well-guarded id_ed25519.pub in case you end up in hot water during the (long - very long, stable cash flow for generations long) maintenance contract, and you’re in the ballpark....
tmux (short for “terminal mux” (short for “multiplexer”)) is i3 for your terminal. Oh, it’s so much more than that, and I recently discovered with some joy that it is installed by default on OpenBSD, but its fundamental value add to any programmer who has to SSH into servers more than once a week is it allows you to split your screen up into multiple independent shells without needing a graphical environment at all....