Book censorship is the act of some authority taking measures to suppress ideas and information within a book. Censorship is "the regulation of free speech and other forms of entrenched authority". Censors typically identify as either a concerned parent, community members who react to a text without reading, or local or national organizations. Marshall University Library defines a banned book as one that is "removed from a library, classroom etc." and a challenged book as one that is "requested to be removed from a library, classroom etc." Books can be censored by burning, shelf removal, school censorship, and banning books. Books are most often censored for age appropriateness, offensive language, sexual content, amongst other reasons. Similarly, religions may issue lists of banned books,