The dog, or the domestic dog (Canis lupus familiaris, formerly Canis familiaris), is a domesticated, bred form of the grey wolf (Canis lupus). It belongs to the class of mammals and to the canine family.
The dog is the first animal domesticated by humans. In the early days of domestication, dogs were useful as watchdogs and as scavengers. Dogs have been and are still used to help pull carts and sleds and in herding and hunting. Today, dogs have an even wider variety of roles, working as drug detection dogs, guide dogs, diabetic alert dogs and rescue dogs, for example. Many of these roles make use of the dog’s keen sense of smell.