I legitimately back up my history file. Mostly because it likes to truncate itself randomly (though this may have been fixed in zsh, or my config, because it's been a while). Just a systemd timer that triggers a shell script to copy it by date and rotate anything older than 100 copies.
Edit: WHY DID I SAY ANYTHING? After like 3 months of no problems, my history truncated itself to 3 entries a few minutes ago. I've only ever seen a few days of loss before that lol.
That's one thing I like about zsh, or my config at least, because I use i3 and therefore tend to open lots of shells. History is mostly local until I hit return twice (two empty prompts) at which point I can get history from other sessions. It's stuck more global at that point though aside from future history.
Was working on a server where I did not want to put some dumb command into the history, so I add a space like you do. Press up. The command is there. The fucking insult I felt.
history displays a list of all commands you have run on the terminal since the history list was last cleared. It is invaluable for referring back to a big complex command or set of commands you ran at some point in the past. The -c flag clears that history.
(I'm not too familiar, someone else can clarify: is this available outside bash?)
What's interesting to me is the -a option, which lets you "flush" the history for the current session without ending the session. I can see that being useful!