Biting anything that is not the designated chew toy is bad dog behavior. Biting is a natural canine dominance behavior used to communicate each dog's standing within the pack. In order to correct the aggressive biting and chewing behaviors, the family must understand them first.
Don't Allow Your Puppy To Bite
When a puppy is introduced into your home, they often nip or bite in what is often thought of as play. What they are really trying to do is establish their role among their new pack, your family. From the day they were born, they used the nipping, biting and chewing as a way to communicate to their litter mates their particular station within the litter. Now that they've moved into a new pack, the puppy is using the only way it knows to establish his place among the family. It is at this point that you should take an active role in discouraging these activities. It is never okay for the puppy or dog to use their teeth on human skin.
Maintain Dominance Over Your Dog
Even as a dog grows older, he may try to mouth your hand or your clothing. He is testing his boundaries, trying to assert his dominance over the person. It is important to correct him at that point because if left unchecked, he will continue to push toward more aggressive dog behavior and potentially a tragic outcome.