- An hour is 60 minutes.
- The hours between 12 midnight and 12 noon are A.M. (ante “before” meridiem).
- The hours between 12 noon and 12 midnight are P.M. (post “after” meridiem)
- Sailor time is used on a ship at sea. The day is divided into 5 “watches” of 4 hours each and 2 of 2 hours each. Bells tell the time. One bell marks the first half-hour of the watch; 8 bells toll the last. On ship, the new day starts at noon.
- Military time is based on a 24-hour clock, making 3:00 P.M. 1500 hours.