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.