A date is a reference to a particular day represented within a calendar system, and consists of year, month and day.
A date is an ambiguous interval in time, which usually refers to a day, month and year in a particular calendar system.
A date by itself (such as
Jan 1 2020) does not refer to a specific moment in time.
- It does not have a time of day, so it refers to a whole calendar date.
- It does not specify a time zone, so it could be interpreted differently by each viewer.
Related concepts such as "today", "yesterday", and "tomorrow", or any individual day of the week such as "Monday" or "Tuesday", also have the same qualities. They are loose terms that require a time zone in order to lock in to a specific range of time.