Sometimes the reason for biting can be found in the environment. Toddlers need space. They cannot stand being crowded together and may take out their frustrations on another child. So try to give children lots of space, whenev er possible. Remember, some young children don't understand how to create more space.
Grownups are important role models.
Never tell a child who has been bitten to bite back. Then you have two children in pain, twice the problems and have taught that violence is the way to react to violence.