Banned Books Week 2018
All of the books depicted in the above graphic have at one time or another been banned or removed from the bookshelves of school libraries or public libraries because of challenges from the public.
Usually the attempt to censor stems from the fact that a book simply expresses ideas that disagree with the would-be censor's view of the world. The ALA annually releases a list of the ten most challenged books from the previous year. This year they have produced a video introducing those books and the reasons that they were challenged. Here is that video.