An ISBN (International Standard Book Number) is a 13-digit code used to uniquely identify books and other published materials worldwide. It’s essential for book sales, distribution, and cataloging by retailers, libraries, and distributors. Each edition and format of a book (e.g., paperback, hardcover, eBook) requires its own ISBN. On the other hand, an LCCN (Library of Congress Control Number) is assigned by the Library of Congress and used mainly by libraries in the United States to catalog and organize books before publication. While an ISBN is required for commercial book distribution, an LCCN is optional but helpful for increasing a book’s visibility and accessibility within library systems. Together, these identifiers help establish your book’s legitimacy and expand its reach.
To obtain an ISBN, you need to apply through the official ISBN agency in your country. In the United States, ISBNs are issued by Bowker (MyIdentifiers.com). You can purchase a single ISBN or a block of multiple ISBNs if you plan to publish more than one edition or title. Once purchased, you’ll receive a unique number that you can assign to your book’s format (e.g., print, eBook). This ISBN is then used to register and track your book through global sales and distribution channels.
To get an LCCN (Library of Congress Control Number), you must apply through the Preassigned Control Number (PCN) Program offered by the Library of Congress (loc.gov/publish/pcn/). You must be a U.S.-based publisher, and your book must be intended for distribution in the United States. Once approved, the LCCN will be issued before your book is published and should appear on the copyright page. Submitting a copy of the finished book to the Library of Congress may be required as part of the process.
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