A Temporal.DateTime represents a calendar date and wall-clock time, with a precision in nanoseconds, and without any time zone.
Of the Temporal classes carrying human-readable time information, it is the most general and complete one.
Temporal.Date, Temporal.Time, Temporal.YearMonth, and Temporal.MonthDay all carry less information and should be used when complete information is not required.
“Calendar date” and “wall-clock time” refer to the concept of time as expressed in everyday usage.
Temporal.DateTime does not represent an absolute, unique point in time; that is what Temporal.Absolute is for.
One example of when it would be appropriate to use Temporal.DateTime and not Temporal.Absolute is when integrating with wearable devices.
FitBit, for example, always records sleep data in the user’s wall-clock time, wherever they are in the world. Otherwise they would be recorded as sleeping at strange hours when travelling, even if their sleep rhythm was on a healthy schedule for the time zone they were in.
A Temporal.DateTime can be converted to a Temporal.Absolute using a Temporal.TimeZone.
A Temporal.DateTime can also be converted into any of the other Temporal objects that carry less information, such as Temporal.Date for the date or Temporal.Time for the time.