An hour is most often described as a span of time equal to 60 minutes, although a minute is equal to 60 seconds and a second has a strict scientific definition. There are also 24 hours in the day. The majority of individuals read time using a 12-hour or 24-hour clock.

12-hour clock:

A 12-hour clock employs the digits 1-12.  Depending on the clock, most analog clocks or watches may not indicate whether it is morning or evening.  On digital clocks and watches, “AM” stands for ante meridiem, which means “before midday,” and “PM” stands for post meridiem, or “after noon.”  By convention, 12 a.m. symbolizes midnight, whereas 12 p.m. represents noon.  Using the words “12 midnight” and “12 noon” can help to avoid ambiguity in situations where a person is unfamiliar with norms.

24-hour clock:

A 24-hour clock commonly utilizes the digits 0–23, with 00:00 indicating midnight, and a day running from midnight to midnight over 24 hours. This time format is an international standard that is frequently used to eliminate the uncertainty caused by the usage of a 12-hour clock. The hours 0-11 represent the AM hours on a 12-hour clock, whereas the hours 12–23 represent the PM hours. In some nations, 24-hour time is referred to as military time, because it is the time format used by militaries (and other entities) all over the world, when precise time measurement is critical.

Hours in different time periods