What is "american staffordshire terrier"

The American Staffordshire Terrier, also known as Amstaff (in USA) or simply Stafford, is a medium-sized, short-coated American dog breed. It is one of several breeds commonly known as pit bulls. In the early part of the twentieth century the breed gained social stature and was accepted by the American Kennel Club in 1936. The name was changed to reflect difference from the Staffordshire Bull Terrier of England.