It is believed that the custom of dividing the cycle of day and night into 24 periods began with the ancient Egyptians.Ĭurrent use: The hour is used globally as a unit of time. There have been many definitions of the hour throughout history based on culture or region, such as the hour being divided into 1/12 of a period daylight or darkness. History/origin: The term 'hour' is derived from the Anglo-Norman 'houre,' which was in use around the 13 th century.
In Coordinated Universal Time, a negative or positive leap second may be incorporated to keep the hour within 0.9 seconds of universal time, making an hour either 3,599 or 3,601 seconds in some cases. Definition: An hour (symbol: h) is a unit of time conventionally defined as 1/24 of a day and 3,600 seconds.
