Breeders

Dog breeding is the practice of mating selected specimens with the intent to maintain or produce specific qualities and characteristics.

Humans have maintained populations of useful animals around their places of habitat since pre-historic times. They have intentionally fed dogs considered useful, while neglecting or killing others, thereby establishing a relationship between humans and certain types of dog over thousands of years. Over these millennia, domesticated dogs have developed into distinct types, or groups, such as livestock guardian dogs, hunting dogs, and sighthounds. To maintain these distinctions, humans have intentionally mated dogs with certain characteristics to encourage those characteristics in the offspring.
Through this process, hundreds of dog breeds have been developed. Initially, the ownership of working and, later, purebred dogs, was a privilege of the wealthy. Nowadays, many people can afford to buy a dog. Some breeders chose to breed purebred dogs, while some prefer to produce crossbred dogs, claiming that the outcross is healthier than original breeds, and avoiding linebreeding or inbreeding.

(from Wikipedia)