24-hour time

24-hour time, or the 24-hour clock, is the notation of time on a 24-hour system, without using a.m. or p.m. to denote morning/afternoon. Thus 8 am is given as 08.00h, and 8 pm as 20.00h.

This is also known as "military time." Presumably to avoid deadly mistakes, the military uses unique time hours rather than duplicates with "a.m." and "p.m." designations.