Books have been banned as long as there have been books and continue to be banned or challenged even today. A banned book is a book that may be:
The most extreme form of banning is the death or demand for the death of the author, as during the Inquisition, or more recently with Salman Rushdie.
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. As such, they are a threat to freedom of speech and choice.
In the United States, your right to read what you want is protected by the First Amendment. In a free society, the author and reader are protected.