RPO

Recovery point objective is how much data you have decided you can afford to lose.

If you back up nightly, you have chosen to accept losing up to a day's work, whether or not anybody framed it that way. That is usually the useful conversation: not a technical discussion about backup frequency, but a business one about how much re-keying, lost orders or missing records is tolerable. Most organisations have made this decision implicitly, by inheriting a schedule, rather than deliberately.