duration

Durations are measurements of defined periods of time. If the end has already occurred, then they can be exact; otherwise they are predictions, and some imprecision is necessarily included.

A completed journey has both endpoints in the past. A planned lifetime has an expected end, so its duration expresses a design expectation even before the object reaches that age.

The start and end distinguish durations within one operation. Time spent traveling can differ from the total time between joining a queue and leaving the destination.