Use the resources listed in this guide to begin your research about banned and challenged books. Pay close attention to the search tips and examples provided on each page. They will help make your research more successful. If you are having trouble, ask a librarian for help.
A challenge is an attempt to remove or restrict materials, based upon the objections of a person or group. A banning is the removal of those materials. From ALA's "About Book Bans and Challenges"