It is called kilometer to a unit used to measure lengths and that is equivalent to A thousand meters. It is, therefore, one of the multiples of the unit known as meter.

The kilometer symbol is km, both singular and plural (1 km, 3 km, 568 km) and it is important to note that it is not an abbreviation; this means that a period should not be included at the end. It must be written, on the other hand, always with lower case to avoid confusion with the symbol of the Kelvin (K), a unit of temperature.

One kilometer is equivalent, compared to other units, at 0.621 miles, 1,093.61 yards, and 3,280.83 feet, for example. It should be noted that these equivalences are not exact, but rather are approximations.

According to International System of Units, a kilometer equals 10 hectometres, 100 decameters, 1,000 meters, 10,000 decameters, 100,000 centimeters and 1,000,000 millimeters.

For logical reasons, distances between cities or countries are usually expressed in kilometers. For instance: “Buenos Aires is 404 kilometers from Mar del Plata”. That same phrase, reflected in meters, would be more complicated to express: “Buenos Aires is 404,000 meters from Mar del Plata”.

The speed of automobiles is also expressed, for similar reasons, in kilometers per hour: “I bought a new car that reaches 220 kilometers per hour, although I cannot test it since in my city you cannot exceed 100 kilometers per hour”. If the speed of cars were measured in meters per hour, figures such as 220,000 meters per hour or 100,000 meters per hour would be handled.