Pit bull is the common name for a type of dog. Although the lists of breeds often considered in North America to be of the pit bull type include the American Pit Bull Terrier, American Staffordshire Terrier, Staffordshire Bull Terrier, and The American Bulldog, The true "Pit Bull" is The American Pit Bull Terrier

In the early 20th century pit bulls were used as catch dogs in America for semi-wild cattle and hogs, to hunt, and drive livestock, and as family companions. Due to unscrupulous breeding - many are too aggressive for their original purpose.

Always fully research the breeder and bloodline prior to purchasing one of these nobel canines.

More Info: en.wikipedia.org