24 hour system, is one kind of time representation method. It is distinguished from the 12-hour system.

In the 24 hour system, 1 PM is written as 13 PM. 2 p.m., was written at 14 p.m.

In life, though, We Use the 12-hour clock more often than not. for example We said, close at 5 p.m.

We say that "9 to 5" means 9 a.m. and 5 p.m. (when ordinary employees go to and from work).

However, in the strict definition of the scientists, in the contract and other legal documents, the time should be written in 24 hours.

Twelve-hour is a time rule that divides the twenty-four hours of the day into two periods, a.m. (Latin ante meridiem for before noon) and p.m. (Latin post meridiem for after noon). Each period consists of twelve hours, expressed in the order of Number 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. The morning session is from midnight to noon, while the afternoon session is from noon to midnight.