The adder is the only venomous snake native to the United Kingdom. Also called the common European adder or common European viper, it is scientifically known as Vipera berus and belongs to the viper family Viperidae.
Adders are one of only three snake species native to Great Britain. The other two—the grass snake and the smooth snake—are non-venomous. Adders occur in habitats such as heathland, moors, woodland edges, rough grassland, and coastal dunes, provided there are sunny places for basking.
Despite having venom, adders are generally shy and avoid people. They usually bite only when cornered, stepped on, handled, or otherwise provoked. Bites can be painful and require medical attention, but fatalities in Britain are extremely rare.
The species is adapted to cold climates and has an exceptionally broad range, extending across much of Europe and into northern Asia. In Britain, adders are legally protected under the Wildlife and Countryside Act 1981, reflecting concerns about habitat loss, disturbance, and population declines.