1kilometre
The kilometre, symbolised as km, is a unit of length in the metric system. It is equal to one thousand metres. The kilometre is the most commonly used unit for measuring distances between geographical locations, such as between cities or countries. It is also frequently used for measuring distances travelled by vehicles, such as cars or bicycles, and for altitude in aviation.
The kilometre was established as part of the metric system in France in 1795. Its definition has
The kilometre is also used in various scientific and engineering fields. In astronomy, it can be used