Cross country, trail and mountain running is the sport of running over unpaved, natural terrain. Traditional cross-country is run primarily on grass in parks or across open countryside, involving multiple laps of a relatively short distance. Trail races are more typically single loop, or point-to-point events. The paths are narrower, the footing rougher, and the hills steeper than might be experienced in traditional cross-country. Mountain races tend to feature more extreme forms of uphill and downhill running. They may be uphill only races, usually from the bottom to the top of a mountain; or they can include both uphill and downhill sections. Ultra trail running refers to distances beyond a marathon (42.2K), most commonly 50K, 50 miles, 100K, or 100 miles.
The short lap format of cross country makes it suitable for young children as well as older athletes, whereas trail and mountain races cater primarily to adults.
