Most UK nature reserves are administered by county-based wildlife trusts, charitable organisations, though a few are more local, run by the council or other groups, while the RSPB have a separate collection of riparian reserves. There are also a number of national nature reserves, which protect larger or more scientifically important sites, and these are managed by the government and/or the National Trust. The national reserves are not necessarily the most photogenic or scenically interesting places, however, and some are poorly signed, often with limited access; instead it is the wildlife trust reserves that tend to be the most well-known, and varied. Although primarily managed for plants and wildlife - typically birds, insects, amphibians, reptiles, small mammals, fish and other aquatic species - many, perhaps half of them, are also of interest for the natural landscapes, either within the reserve itself, or the immediate surroundings.


Nature reserves may contain meadows, ancient woodland, heath, gorges, hills, lakes, wetlands, coastline, abandoned railway lines and old quarries, and in southwest UK they range in size from a few acres, for example the seven acre Badgeworth Nature Reserve near Gloucester, protecting a rare buttercup species, to several hundred acres, such as Lower Woods or Lancaut. All are free to enter and virtually all are open all year without restrictions; only a very few need permission to access, or are currently closed to the public. Some charge a fee for parking, however. For about half of the reserves, the main reasons for visiting - the plants and wildlife - are seasonal, so such places are not generally of interest from late autumn to early spring, while others are worthwhile any time of the year. Most nature reserves are not well signposted, perhaps marked only by a small sign at the entrance, usually but not always accompanied by a map and information board, so visits generally need to be researched in advance.

In southwest England, nature reserves are concentrated in geologically interesting regions, especially the Cotswolds, the Mendip Hills, the Quantock Hills, Exmoor, Cranborne Chase, and along the coast, while in south Wales they are more evenly distributed, reflecting the generally more rural landscapes.