Often known as military time, 24-hour time is used by many countries. It begins at midnight with 0000 and the day ends with 2359. The first two digits represent the hour and the last two digits represent the minutes. Since there are 24 hours in a day, each hour is numbered 00 through 23. For instance, 0100 is 1:00 A.M., 1200 is noon, 1300 is 1:00 P.M., and 2043 is 8:43 P.M.