When receiving a datetime from another software or from a user, it will probably be in a string format. Formats such as JSON don't even define how a date should be represented, but it's usually a best practice to provide those in the ISO 8601 format.
The ISO 8601 format is usually defined as [YYYY]-[MM]-[DD]T[hh]:[mm]:[ss]+-[TZ], for example 2018-03-19T22:00+0100 would refer to March 19 at 10 P.M. on the UTC+01:00 time zone.
ISO 8601 conveys all the information you need to represent a date and time, so it's a good way to marshal a datetime and send it across a network.
Sadly, it has many oddities (for example, the +00 time zone can also be written as Z, or you can omit the : between hours, minutes, and seconds), so parsing it might sometimes cause trouble.
