A unique numeric commercial book identifier. It is designed to help publishers, booksellers, libraries, and internet retailers track inventory, manage orders, and facilitate distribution. Since 2007, all ISBNs have been 13 digits (previously 10 digits). A standard ISBN-13 is divided into five distinct parts:
| Element | Description |
| GS1 Prefix | A 3-digit number (978 or 979) is used to identify books in the book industry. |
| Registration Group | Identifies the country, geographic region, or language area. |
| Registrant | Identifies the specific publisher or imprint. |
| Publication | Identifies the specific edition and format of a title. |
| Check Digit | A final single digit used mathematically to validate the rest of the number. |
Essential Facts
- 1k format (e.g., one for the hardcover, one for the paperback, and one for the EPUB).
- Non-Reusable: Once assigned to a title, an ISBN can never be reused, even if the book goes out of print.
- Administration: The system is coordinated by the International ISBN Agency, based in London, while local agencies (such as Bowker in the U.S.) manage assignments within specific regions.
Note: While an ISBN is necessary for most retail distribution, it does not provide copyright protection. Copyright is a separate legal status.
