There are hundreds of long-distance footpaths in the United Kingdom designated in publications from public authorities, guidebooks and OS maps. They are mainly used for hiking and walking, but some may also be used, in whole or in part, for mountain biking and horse riding. Most are in rural landscapes, in varying terrain, some passing through National Parks and Areas of Outstanding Natural Beauty. There is no formal definition of a long-distance path, though the British Long Distance Walkers Association defines one as a route "20 miles [32 km] or more in length and mainly off-road." They usually follow existing rights of way, often over private land, joined together and sometimes waymarked to make a named route. Generally, the surface is not specially prepared, with rough ground, uneven s