Recovery point objective (RPO)

Recovery point objective (RPO) is the point in time relative to the failure to which you need preservation of data. Data changes preceding the failure or disaster by at least this time period are preserved by recovery processing. Zero is a valid value and is equivalent to a "zero data loss" requirement.

RPO values are:

Last save (weekly, daily, ...)
Start of last shift (8 hours)
Last major break (4 hours)
Last batch of work (1 hour to tens of minutes)
Last transaction (seconds to minutes)
In-flight changes may be lost (power loss consistency)
Zero data loss