The following information was found Dog Wikipedia.

Dogs are considered domestic animals. Their name comes from “Canis lupus familiaris”. As you might know, it is the most common terrestrial carnivore. Very long ago, the dog and the extant gray wolf had multiples similitudes, however modern wolves and domestics animals are now not closely related. This statement suggests that the direct ancestor of the dog is extinct.

It is very important to note that dogs are the first species to be domesticated. Since, humans had used animal breeding to develop the characteristics desired in a dog. Dogs come in a variety of shapes, sizes and forms and play different roles with humans. For instance, they are used for protection, for hunting, for aiding handicapped individuals and many others. They are extremely appreciated by people. In fact, they are so loved that they are often referred as “man’s best friend”.

huge dog
A representation of how important dogs are to humans (Kellepics)