One kilometer is a unit of measurement in the metric system, equal to 1,000 meters. It is commonly used to measure distances, especially in countries that use the metric system. For example, a standard marathon race is approximately 42 kilometers long, which is about 26 miles. In everyday terms, 1 kilometer is roughly equivalent to 0.62 miles. This means that if you were to walk or run a distance of 1 kilometer, you would cover a little more than half a mile. Many road signs in places like Europe and Canada display distances in kilometers to help travelers gauge how far they need to go.