ISBN is an acronym for International Standard Book Number. As the name implies, ISBNs are international, meaning they are recognized in all countries regardless of where the corresponding books are published. ISBNs are assigned locally, however; each country has one designated ISBN agency to assign ISBNs for publishers and self-publishers in that country. For the United States and its territories, that agency is Bowker.
If you wish to sell your book in brick-and-mortar stores or online; to place your book with a wholesaler; and/or to place your book in libraries, your book will need an ISBN assigned to it. An ISBN is also necessary if you wish to list your book in Bowker’s Books in Print, the main source used by booksellers and libraries to search for and order books. The listing in Books in Print contains information about the book itself, as well as ordering and correspondence information. The ISBN is printed on the copyright page of your book and on the back cover (either by itself or as part of a barcode).
If you wish to release different versions of your book (e.g., softcover, hardcover, eBook), each version must have its own ISBN. This is also true for future editions of your book or if you reprint your book with a different publisher in the future. A reprint of your book that is the same as the original printing or contains only minor typographical corrections can use the ISBN originally assigned.
ISBNs are typically purchased by the self-publisher or publisher and they are not transferable. Some publishers, especially self-publishers, will allow authors to purchase their own ISBNs to be used on their books. Such authors will likely wish to buy just a single ISBN, which is more expensive because the per-ISBN price decreases when the numbers are purchased in bulk. The ISBN is NOT related to the copyright. Unless specified otherwise by the book’s publisher, the author of the book owns the copyright regardless of who purchases the ISBN.
Some publishing companies, especially online self-publishers, claim to be Bowker agents authorized to purchase single ISBNs in an author’s name at a lower price than that listed at the Bowker ISBN website. Be very wary of any publisher making such claims. From the Bowker website:
Bowker is the official ISBN Agency for publishers physically located in the United States and its territories …. If an ISBN is obtained from a source other than the official ISBN Agency, it might not identify the publisher of the title accurately.
Bloated Toe Publishing provides ISBNs (purchased directly from Bowker) for all books we publish. Once a book is published and available for sale, we enter all information into the Bowker Books in Print database. However, we will, at the author’s request, use an ISBN owned and provided by the author. In this case, the author will be responsible for entering the book’s information into the Books in Print database.