Kilometer (km)
Definition: A kilometer (symbol: km) is equal to 1,000 meters. It is a unit of length in the SI system derived from the base unit meter using the prefix kilo-, which denotes a factor of 1,000.
History/origin: The kilometer emerged alongside the metric system in France in the late 18th century. As trade and travel expanded, a larger practical unit of distance was needed beyond the meter, making the kilometer a natural and convenient choice.
Current use: Kilometers are widely used to express distances between geographic locations in most countries that use the metric system. Road signs, maps, and navigation systems in Europe, Asia, Africa, and most of the Americas display distances in kilometers.
