Look at it. Does it look like its head belongs on a much bigger dog? And its eyes face to the side? That would be a Bull Terrier. Does it look like the most common, but smaller? American Staffordshire bull terrier. Or is it the most common looking? About 70, or 80 lbs.? American Stafforshire pit bull terrier. The fourth, American Pit, is not real common anymore. I have not seen or heard of one of those in quite some time. Now, if you have the most common, it's markings, and nose will tell the tale. The American Staffordshire Pit bull terrier, will either be brindle, the brown stripes, and a black nose. That would be a Brindle. A red, or pink, nose is a red nose. If the dog is grey, or a real light brown, and the nose looks black, that would be a blue nose. A pit has to have white on their head somewhere. A white chest, and at least 1 white paw, to even be considered, as a purebred. The white comes from it heritage. The white terrier, which is now extinct, by the way. The other half of their blood comes from the English bulldog.........Chuck.