Original: Where convenient, the notation 24:00 may also be used to refer to midnight at the end of a given dateâ "that is, 24:00 of some day is the same time as 00:00 of the following day.
Simplified: Midnight is called 24:00 if used to mean the end of the day and 00:00 if used to mean the beginning of the day. For example, you would say "Tuesday at 24:00" and "Wednesday at 00:00" to mean the exact same time.