Goodreads, a social networking site for book readers, claims to be the largest site for book recommendations in the world. As of 2016, Goodreads had 55 million members who added more than 1.5 billion books to their "shelves". The book data itself comes from a variety of sources, including Amazon, Barnes & Noble, Ingram, Library of Congress, WorldCat, and others alongside data submitted by individual publishers and Goodreads users.