DATE
Calendar expressions such as 'October 7, 1991', '22/01/2018', or '1992'; also relative expressions like 'Two days ago'.
TIME
Points in time ('At seven o'clock', '22:30', '3.30pm'...), absolute or relative ('Half an hour ago', 'In two minutes and three seconds')
SET
Repetitions in time (such as 'Monthly', 'Twice a week', 'Every Monday', 'Three times a year', 'Every first of the month'...)
DURATION
Amounts of time like 'Two days', 'Three years and six months', 'Two centuries', 'One hour and 20 minutes' or 'Half an hour'.