The marathon is a long-distance foot race with an official distance of 42.195 kilometers (26 miles 385 yards) that is usually run as a road race.

The marathon was one of the original modern Olympic events in 1896, though the distance did not become standardised until 1921. More than 800 marathons are contested throughout the world each year, with the vast majority of competitors being recreational athletes. Larger marathons can have tens of thousands of participants.