According to ALA.org:
Banned Books Week is an annual event celebrating the freedom to read. Typically held during the last week of September, it highlights the value of free and open access to information. Banned Books Week brings together the entire book community –- librarians, booksellers, publishers, journalists, teachers, and readers of all types –- in shared support of the freedom to seek and to express ideas, even those some consider unorthodox or unpopular.
By focusing on efforts across the country to remove or restrict access to books, Banned Books Week draws national attention to the harms of censorship. Check out the frequently challenged books section to explore the issues and controversies around book challenges and book banning.
Banned Books Week 2012 marks its 30th anniversary (see timeline). Thousands of individuals and institutions across the United States participate in Banned Books Week each year, and it has grown into a premier literary event and a national awareness and advocacy campaign around censorship. In honor of the 30th anniversary of Banned Books Week, the Office for Intellectual Freedom delivers the 50 State Salute to Banned Books Week in coordination with ALA Chapters.
The 50 State Salute consists of videos on how each state celebrates the freedom to read. For more information on how your organization can participate, please visit the 50 State Salute page. And for the second year in a row, we are cosponsoring the Banned Books Virtual Read-Out, where readers can declare their freedom to read by uploading videos of themselves reading from their favorite banned/challenged books. The criteria and video submission information has been updated. Please check out the Banned Books Week Virtual Read-Out page for more information.