The Viperidae (vipers) are a family of venomous snakes found in most parts of the world, with the exception of Antarctica, Australia, Hawaii, Madagascar, various other isolated islands, and north of the Arctic Circle. All have relatively long, hinged fangs that permit deep penetration and injection of snake venom. Four subfamilies are currently recognized. They are also known as viperids. The name "viper" is derived from the Latin word vipera, -ae, also meaning viper, possibly from vivus ("living") and parere, referring to the trait viviparity common in vipers but not in snakes at large.
