Pit bull is the common name for a type of dog. Formal breeds often considered in North America to be of the pit bull type include the American Pit Bull Terrier, American Staffordshire Terrier, American Bully, and Staffordshire Bull Terrier. The American Bulldog is also sometimes included. Many of these breeds were originally developed as fighting dogs from cross breeding bull-baiting dogsand terriers. After the use of dogs in blood sports was banned, such dogs were used as catch dogs in the United States for semi-wild cattle and hogs, to hunt and drive livestock, and as family companions. Despite dog fighting now being illegal in the United States, it still exists as an underground activity, and pit bulls are a common breed of choice.
The term pit bull is often used loosely to describe dogs with similar physical characteristics, and the morphologicalvariation amongst "bully breed" dogs makes it difficult for anyone, even experts, to visually identify them as distinct from "non-pit bulls". While mixed breed dogs are often labeled as "pit bulls" 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.