Your puppy has very sharp teeth.
It knows how to use them, but not in a constructive manner (yet!).
If you have ever been bitten by a puppy, you understand how sharp their canines can be. Obviously, it is not the intention of the dog to hurt you. It may have started as a game that quickly turned to be a playtime with painful repercussions.
The following tips should help you learn how to stop your buddy from biting.