Inches
Definition: The inch (symbol: in) is an Imperial and U.S. customary unit of length equal to 1/12 of a foot or 25.4 millimeters.
History/Origin: Derived from the Latin ‘uncia’, meaning one-twelfth part; standardized in 1959 as exactly 25.4 millimeters.
Current Use: Used widely in engineering, manufacturing, and consumer industries for screen sizes and mechanical tolerances.
Feet
Definition: The foot (symbol: ft) is an Imperial and U.S. customary unit of length equal to 0.3048 meters.
History/Origin: Based on the human foot as an early measure of length; standardized in 1959 as exactly 0.3048 meters under international agreement.
Current Use: Widely used in the United States and United Kingdom for height, construction, and aviation measurements.