Slashdot posters would use ^H^H in their posts (backspace)

It goes back way further than that - probably to the dawn of IRC or so.

I believe it dates back to the unix talk(1) program, quite a bit earlier than IRC.

It’s from the dec terminal emulation, VT100. I think specifically when you connected to like an ansi type system with dec mode. Or something like that, the memories are fuzzy

The keystroke certainly does, but I was talking about people inserting ^h and ^w in the middle of conversations, which is a bit harder to nail down, though the practice is older than the parent thought.

^H was backspace on teletypes, which probably dates back to the 1960's.

Ah okay makes sense! It's amazing the gaps in knowledge I still have with a lot of things.

I've used Linux daily for like 15 years now, and I know about control characters, but since I never really used emacs (or readline beyond the copy+pasted command here or there) I just completely missed the meaning.

Not emacs (it means kill-region there, which deletes the text between the cursor and the mark and saves it in a holding area, fairly close to what windows does when you hit ^x, except the holding area is fancier).

This readline behavior follows a Unix tty driver. I'm not sure off the top of my head which one introduced it. I don't think it was on xenix but am pretty sure some 4.x bsd had it.

In days of yore the joke was always ^H^H after IBM/DEC backspace v delete confusion