While the reason why toddlers bite is understandable, the behaviour itself I not tolerable, especially at a crèche or in preschool. Sometimes the habit of biting spreads amongst a playschool group, because toddlers copy behaviour they see and experience. This is why it is important to confront the issue of biting with your child on an individual level.
If your child bites a playmate or sibling, make sure the victim gets a proper apology from your child. Giving all the attention to the child who does the biting will only encourage this kind of behaviour in future. Make sure that your child knows that biting is harmful to other people and that it makes them feel sad and hurt. Even though a two-year-old can't really feel empathy, the concept of being the cause of pain is understood. Encourage your child to come to you, or seek help from a care-giver if they feel that another child has wronged them enough to deserve being bitten.
The response to biting has to be firm, but must not cause a commotion, since it is the reaction from adults that very often spurs children on to misbehave.