Although freedom of expression is enshrined in the Bill of Rights, people still try to ban books that conflict with their values and beliefs. Although it is uncommon for a widespread ban on a book to succeed nowadays, the American Library Association (ALA) fields more than 500 challenges to library materials a year. The most commonly cited reasons are sexual content, offensive language, and "unsuited to age group."

We often think that the process of banning books belongs to an older time, when people could more easily control the media that their children were exposed to. However, despite the profusion of readily available sexually explicit material and offensive language on the Internet and on television, some parents and community leaders still feel that literature can be dangerous and should be controlled or banned, especially in schools. Educate yourself about banned books and freedom of expression by reading widely, including such sources as the ACLU's defense of freedom of expression. The breadth of your knowledge of both literature and politics will help you formulate your own answer to the question, "Why do people ban books?"
Many parents want to control their children's exposure to sexually explicit material and sexual themes in literature. Some feel sexual content is inappropriate for religious reasons, and others challenge a given book because of something specifically objectionable in its portrayal of sexuality. The Color Purple by Alice Walker, Brave New World by Aldous Huxley, and Slaughterhouse Five by Kurt Vonnegut have all been banned or challenged because of sexual content. Books that contain even non-explicit depictions of homosexual relationships are also frequently challenged, either because of implied sexuality or an "anti-family" viewpoint.
Offensive language is a very broad category that encompasses the usual four-letter words, as well as language that nowadays many people find quaint. As recently as 1986, The Grapes of Wrath by John Steinbeck was challenged for using the phrase "God damn," which can now be heard on television and read in the newspapers any day of the week. Racist language is also a target, even if the book in question was written or set during a time period when that language was common. Harper Lee's To Kill a Mockingbird and John Steinbeck's Of Mice and Men have both suffered numerous bans and challenges throughout the years (and still do) for containing profanity and racial slurs.
Two-thirds of challenges and attempts to ban books within the past decade have occurred in classrooms and school libraries. Often, a combination of factors make parents (and less often, administrators) leery of allowing certain books to be taught in a class setting or having a book easily available to students in a school library. For instance, And Tango Makes Three, by Justin Richardson and Peter Parnell, has been at the top of the list of challenged books compiled by the ALA since 2006, a year after its publication. Tango is a picture book that tells the story of two male penguins who formed a pair bond and successfully hatched an egg together. Parents and administrators claimed that the book's content was inappropriate for elementary-school children, despite the authors' stated goal of trying to help children learn about families with same-sex parents.
People also ban books for graphic violence. Ken Kesey's One Flew Over the Cuckoo's Nest was banned from a number of schools in the 1970s for its descriptions of violence, and Native Son by Richard Wright has been challenged multiple times over the past thirty years for the same reason. Descriptions of the occult are also frequently challenged; the Harry Potter series, Lord of the Rings, and Bridge to Terabithia have all been challenged in recent years for occultism and "satanism." Portrayals of drug use, racism, religious viewpoint, and "anti-family" themes are also commonly cited reasons for challenging and banning books.