Since 1982, the last week of September has been designated by the American Library Association as Banned Books Week - Celebrating the Freedom to Read.
From the ALA website:
Even though books are often challenged for the best intentions -- to protect others from difficult or objectionable ideas -- the censorship of books is always dangerous in a democracy. As John Stuart Mill states in In Liberty:
Banned Books Week (BBW) celebrates the freedom to choose or the freedom to express one’s opinion even if that opinion might be considered unorthodox or unpopular and stresses the importance of ensuring the availability of those unorthodox or unpopular viewpoints to all who wish to read them.
As the Intellectual Freedom Manual (ALA, 7th edition) states:“Intellectual freedom can exist only where two essential conditions are met: first, that all individuals have the right to hold any belief on any subject and to convey their ideas in any form they deem appropriate; and second, that society makes an equal commitment to the right of unrestricted access to information and ideas regardless of the communication medium used, the content of the work, and the viewpoints of both the author and receiver of information. Freedom to express oneself through a chosen mode of communication, including the Internet, becomes virtually meaningless if access to that information is not protected. Intellectual freedom implies a circle, and that circle is broken if either freedom of expression or access to ideas is stifled.”
“If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind. Were an opinion a personal possession of no value except to the owner; if to be obstructed in the enjoyment of it were simply a private injury, it would make some difference whether the injury was inflicted only on a few persons or on many. But the peculiar evil of silencing the expression of an opinion is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.”
A book is considered to have been challenged when someone makes an attempt to have it removed from a public or school library, a curriculum or to otherwise limit access to the book in any way. The book is not considered to have been banned unless the challenge is successful and access to the book is restricted in some way.