Banned Books Week -- an annual observance sponsored by the American Library Association and other groups to fight censorship -- begins Sunday and ends Oct. 6.

Banned Books Week events will be held across the U.S. and online in a celebration of literature.

Banning books likely strikes most people as an archaic practice. But many associated with libraries and schools across the country have gone to great lengths to keep certain so-called objectionable works of literature out of patrons’ hands.

While the number of challenged books has been declining steadily since the mid-1990s, there were 326 instances of banned books in 2011, according to the American Library Association, or ALA.

And so, to fight censorship and celebrate Banned Books Week yourself, why not learn more about the most challenged books of last year?

The most banned book last year was Lauren Myracle’s “Internet Girls” series, the ALA reported. Consisting of “ttyl,” “ttfn,” and “l8r, g8r,” the series is written entirely in “Internetspeak,” making heavy use of the kind of abbreviations seen in the book titles. The series follows three high-school students from their sophomore year through graduation, exploring sexuality and the perils of adolescence.

The ALA reported the book has been banned for “offensive language, religious viewpoint, sexually explicit, [and as] unsuited to age group.”

The next most frequently banned book was “The Color of Earth” and its sequels by Kim Dong Hwa. This series of comic books, or graphic novels, follows the lives of a single mother and her daughter in rural Korea.

The coming-of-age story details and illustrates one girl’s rise into maturity and romance. According to the ALA, “The Color of Earth” has been banned for “nudity, sex education, sexually explicit, [and as] unsuited to age group.”

Surprisingly, the popular young-adult series “The Hunger Games” was the third most banned book last year. The series, partially adapted for the major motion picture released in March, centers on a post-apocalyptic future in which children are forced to fight each other for survival. The ALA lists the books as being banned as “anti-ethnic, anti-family, insensitivity, offensive language, occult/satanic, violence.”

Other frequently challenged books last year included timeless classics such as Harper Lee's "To Kill a Mockingbird" and Aldous Huxley's "Brave New World."

For a full list of the top 10 banned books of 2011, either visit the ALA website or view this illustrated guide, broken down by subject matter, at the Huffington Post.