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 remained consistent since then. In many countries, the kilometre is the standard unit for road signs and speed limits. For example, a speed limit might be posted as 100 kilometres per hour.

The kilometre is also used in various scientific and engineering fields. In astronomy, it can be used to measure distances within star systems, although larger units like light-years are more common for interstellar distances. In sports, races are often measured in kilometres, such as a 10-kilometre run. The conversion between kilometres and miles, the imperial unit of distance, is approximately 1 kilometre equals 0.621371 miles. Conversely, 1 mile is equal to approximately 1.60934 kilometres.