Dogs have been selectively bred for thousands of years, sometimes by inbreeding dogs from the same ancestral lines, sometimes by mixing dogs from very different lines. The process continues today, resulting in a tremendous variety of dog breeds.
The following list uses a wide interpretation of "breed". Breeds listed here may be traditional breeds with long histories as registered breeds, rare breeds with their own registries, or new breeds that may still be under development. Please see individual articles for more information.
This working dog is a border collie mix.
A working dog refers to a canine working animal, i.e. a dog that is not merely a pet but learns and performs tasks to assist and/or entertain its human companions, or a breed of such origin.
Arguably the variety of -often exclusive- canine jobs is a better justification for the dog's honorary title "man's best friend" than the more accidental popularity as pet number one in western cultures.
Within this general description, however, there are several ways in which the phrase is used.

Dog breeding is the vocation of mating carefully selected specimens of the same breed to reproduce specific, consistently replicable qualities and characteristics.
Dog anatomy, breeding, breeds, equipment, health, law, monuments, organizations, related professions and professionals, shows and showing, sports, training and behavior, types, working dogs. Dogs in popular culture, famous dogs, fictional dogs, films about dogs, dogs as pets.
