A viper is a type of venomous snake belonging to the family Viperidae, which includes more than 200 species of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, New Zealand, and various other isolated islands. They have long, hinged fangs that permit deep penetration and injection of their venom, which is used to hunt and kill their prey. Vipers are characterized by a pair of long, hollow, venom-injecting fangs attached to movable bones of the upper jaw that are folded back in the mouth when not in use. Their eyes have vertical pupils, and their scales are keeled. Some of the key features of vipers include:

• Hollow fangs: These are used to inject venom into their prey.

• Keeled scales: These are a distinguishing feature of vipers.

• Triangle-shaped head: This is distinct from the neck, owing to the location of the venom glands.

• Nocturnal and ambush predators: Vipers are typically active at night and lie in wait for their prey.

Vipers are a diverse group of animals with a wide range of adaptations depending on their habitat and prey. They are also known for their venomous bites, which can be dangerous to humans.