Saving the current state of a program and its data, including

intermediate results to disk or other non-volatile storage,

so that if interrupted the program could be restarted at the

point at which the last checkpoint occurred. This facility

came into popular use in mainframe operating systemss such

as OS/360 in which programs frequently ran for longer than

the mean time between system failures. If a program run fails

because of some event beyond the program's control

(e.g. hardware or operating system failure) then the

processor time invested before the checkpoint will not have

been wasted.