Dog is the common use term that refers to members of the subspecies Canis lupus familiaris. The term can also be used to refer to a wider range of related species, such as the members of the genus Canis, or "true dogs", including the Wolf, Coyote, and Jackals; or it can refer to the members of the subfamily Caninae, which would also include the African Wild Dog; or it can be used to refer to any member of the family Canidae, which would also include the Foxes, Bush dog, Racoon dog, and others
Some members of the family have "dog" in their common names, such as the Raccoon Dog and the African Wild Dog. A few animals have "dog" in their common names but are not canids, such as the prairie dog.
The English word dog comes from Middle English dogge, from Old English docga, a "powerful dog breed".
Due to the archaic structure of the word, the term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary, reflecting the role of the dog as the earliest domesticated animal
Domestic dogs inherited a complex social hierarchy and behaviors from their wolf ancestors. Dogs are pack animals with a complex set of behaviors related to determining each dog's position in the social hierarchy, and they exhibit various postures and other means of nonverbal communication that reveal their states of mind
These sophisticated forms of social cognition and communication may account for their trainability, playfulness, and ability to fit into human households and social situations, and these attributes have earned dogs a unique relationship with humans despite being potentially dangerous apex predators
