The term pit bull is a generic term used to describe dogs with similar physical characteristics. Usually a "pit bull" is considered one of several breeds including the American Pit Bull Terrier, the American Staffordshire Terrier, the Staffordshire Bull Terrier, Bull Terrier or any mix thereof. In some parts of the world, the American Bulldog and Dogo Argentino are also classified as a "Pit Bull-type" dog, despite major genetic differences. Any dog that is mixed with a "bully breed" may also be called a "pit bull" including those that are descended from the English Bulldog, French Bulldog, Boston Terrier and Cane Corso. The pitbull is not a distinct breed which may make it difficult for experts to identify, and while mixed breed dogs are often labelled a "pitbull" if they have certain physical characteristics such as a square shaped head or bulky body type, visual identification of mixed breed dogs is not recommended by the scholarly community.
Several jurisdictions have enacted breed-specific legislation against pitbulls, ranging from outright bans on the possession of pit bull-type dogs, to restrictions and conditions on pit bull ownership. Research indicates that breed specific legislation is ineffective because it is not the breed of dog that is dangerous; rather, it is unfavorable situations that create dangerous dogs.
Dog breeding is the practice of mating selected dogs with the intent to maintain or produce specific qualities and characteristics. When dogs reproduce without such human intervention, their offsprings' characteristics are determined by natural selection, while "dog breeding" refers specifically to the artificial selection of dogs, in which dogs are intentionally bred by their owners. A person who intentionally mates dogs to produce puppies is referred to as a dog breeder. Breeding relies on the science of genetics, so the breeder with a knowledge of canine genetics, health, and the intended use for the dogs attempts to breed suitable dogs.
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.