Persistent data

Persistent data is data that remains after a program has finished. In desktop machines, it is conventional to refer to data on a disk file as persistent, because it persists after the machine has been turned off.

Data in RAM is volatile, because it is lost when power is removed. On a handheld machine, these distinctions are less clear (because the “disk” is itself in RAM). It is, nevertheless, useful to refer to data in files as persistent.