Books are kept on shelves in a special order so they are easy to find. Public libraries have lot of books on various topics including story books and many others. Many public libraries have books and CDs about learning English. Stories are kept in alphabetical order by the last name of the person who wrote them, the author. Books about other things are often given a special number, that refers to what they are about. They are then put on the shelf in number order. One number system used by many libraries is the Dewey decimal system.