Road running is the sport of running on a measured course over an established road (as opposed to track and field and cross country running).
These events are usually classified as long-distance according to athletics terminology, with races typically ranging from 5 kilometers to 42.2 kilometers in the marathon. They may involve large numbers of runners or wheelchair entrants. The three most common IAAF recognized distances for "road running" events are 10K runs, half marathons and marathons. Despite this, there are far more 5K road race events, due to their popularity for charity races and similar, less competitive reasons to hold an event.
Road running may offer those involved a range of challenges and interests such as dealing with hills, sharp bends, varied surfaces, inclement weather, and involvement in a large group. Aerobic fitness, or the ability of the body to use oxygen, is the biggest factor contributing to success.
Race courses are usually held on the streets of major cities and towns, but can be on any road. The IAAF recognizes nine common distances for road races: 10 kilometres (6.2 mi), 15 kilometres (9.3 mi), 20 kilometres (12 mi), half-marathon (21.097 km or 13.1 mi), 25 kilometres (16 mi), 30 kilometres (19 mi), marathon (42.195 km or 26.2 mi), 100 kilometres (62 mi), and Ekiden marathon relay. Other common distances include 5 kilometres (3.11 mi), 8 kilometres (4.97 mi), 12 kilometres (7.46 mi), and 10 miles (16.09 km).