A book ban refers to the prohibition or restriction imposed on the distribution, sale, or access to a particular book or a group of books. This censorship can be implemented by governments, institutions, or communities for various reasons, often with the aim of controlling or suppressing certain ideas, opinions, or information contained within the banned books.
"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. Challenges do not simply involve a person expressing a point of view; rather, they are an attempt to remove material from the curriculum or library, thereby restricting the access of others." The American Library Association
"Censorship is the suppression of content or ideas – and it happens when one group imposes their beliefs on another. Banning books is a type of censorship, but the act can take many forms. Removing a book from the shelf isn’t the only method that amounts to censorship – requiring parental permission to read it or moving it to a less accessible section are both examples of soft censorship." The ACLU of New Jersey
