Trail running is a sport which consists of running and hiking over trails, often in mountainous terrain, with large ascents, descents and varying terrain. Distances in races differ widely, from 5 km to over 100 km. Many high-profile trail races are of ultramarathon distance. Most trail races only have a single stage, where competitors are timed over the entire duration of their run. However, trail running stage races also exist. These multi-day stage races usually offer support and amenities between stages.