Banned Books Week was launched in 1982 in response to a sudden surge in the number of challenges to books in libraries, bookstores, and schools. Held in the last week of September or first week of October, the annual event highlights the value of free and open access to information and brings together the entire book community — librarians, educators, authors, publishers, booksellers, and readers of all types — in shared support of the freedom to seek and to express ideas.

source: https://bannedbooksweek.org/about/