Pit bull is a word used to describe several breeds of dog. This includes the American Pit Bull Terrier, American Staffordshire Terrier, and Staffordshire Bull Terrier, and dogs with a mix of these breeds. In some places also call the modern American Bulldog and Bull Terrier as a "pit bull-type dog". Pit bull can also mean dogs that were known as "bull terriers" before the development of the modern Bull Terrier in the early 20th century.
Pit bulls were bred for pit fighting, which is a sport where dogs fight each other. Pit bulls are very strong, and can pull 30 times their weight.