The time during which a job is processed by the computer is

The stretch during which the processor actually runs and completes a job is its execution time.

Delay time refers to waiting before processing begins, not the processing itself.

Real time describes systems that respond instantly, a different idea.

Down time is the period when a machine is not working at all.

Execution time is measured from the start to the finish of the actual run.

Add-on: total elapsed time including waiting and input output is called turnaround time.