Hour
Abbreviation/Symbol:
h
hr
Unit of:
Worldwide use:
Hours are universally recognized unit of time worldwide. The concept of dividing the day into 24 equal parts has been used for centuries.
Definition:
An hour is a unit of time defined as 3600 seconds (which is also 60 minutes). The concept of dividing the day into 24 equal parts was refined by the Greeks and Romans who used sundials to track the passage of time.
In modern times it is a product of these historical developments and is universally recognized in the International System of Units (SI) as a non-SI unit accepted for use with the SI.
Origin:
The Egyptians were the first to formally divide the day into smaller parts using a sundial to segment daylight into 12 parts which they called hours. This was based on their duodecimal system which is thought to have been influenced by the 12 lunar cycles in a year or the 12 finger joints on a hand. The night was similarly divided into 12 hours resulting in a 24-hour day.
Common references:
1 hour = 3600 seconds (s)
1 hour = 60 minutes
24 hours = 1 day
Usage context:
The hour is used across the globe in various contexts serving as a cornerstone for daily scheduling and time management. Hours are crucial for structuring the workday and calculating labor costs.