The International Standard Book Number (ISBN) is an internationally recognized code for books or independent publications (except periodicals). Publishers can clearly identify all non-periodical books by the international standard book number. An ISBN has only one or one corresponding publication. If the new edition doesn't change much on the basis of the original edition, it won't get a new ISBN when it is published. When the paperback edition is changed to the hardcover edition, the original ISBN number should also be recovered.