What species is the domestic dog?

Up until the late 20th century, dogs had been classified as Canis familiaris domesticus.

In the late 20th century, DNA testing became common. Dogs' DNA was tested, and surprisingly was found to be identical to Grey Wolf DNA. The latin name for wolf is lupus, so the new classification has become Canis lupus familiaris.

The sub-species designation, 'familiaris' implies that the dog has, over the centuries, become familiar or friendly toward humans.