Road Running

Road running is the sport of running on a measured course over an established road (as opposed to track and cross country running). These events would be classified as long distance according to athletics terminology, with distances typically ranging from 5 kilometers to 42.2 kilometers in the marathon. They may involve large numbers of runners or wheelchair entrants.

Marathon
The marathon is a long-distance running event with an official distance of 42.195 kilometers miles and (385†yards), that is usually run as a road race. The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon (the namesake of the race) to Athens.

The marathon was one of the original modern Olympic†events in 1896, though the distance did not become standardized until 1921. More than 500 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.
Source: Wikipedia