Understanding Bloodlines

About bloodlines and famous APBT dogs. When one goes out to purchase an American Pit Bull Terrier, you are often confronted by the “term” different bloodlines that are available today. When advertised, one finds that the breeder often mentions that the pups are Bolio, Frisco, Yellow, Mayday, Redboy, and many old bloodline fingerprints to, Carver, Spike, Hank ect.  Where do these names come from? What do they mean?