Yes, they help the original breeder or a buyer know her parents, her full breed, and the breeder. As an example, one of my chickens is the son a Brown Red Jimmy East Grey cross, and a brown red McLean cross. His bands or a certain number, written in a book, that tell usexactly who his parents are, and who their parents are. As most people write the numbers in books, it’s be close to impossible to track the band, unless it has more than numbers on it. If it had certain letters/names it might be able to be traced, since they had to enacting those bands online.