What is an ISBN?

Ben Anderson
Ben Anderson
Content Writer @BooxAI

What is an ISBN? An International Standard Book Number (ISBN) is a unique numerical identifier attributed to books for their commercial sale and distribution. It is used as a product identifier by digital and physical libraries, online retailers, booksellers and publishers for a variety of different purposes, including inventorying, ordering, listing and selling. Users who access these libraries or stores can also use ISBNs to identify the edition, version or title of the book that they are seeking. A unique ISBN will be assigned to the eBook version, audiobook version, paperback version, and hardback version of the same book. Once an ISBN is assigned, it can never be re-issued to another publication again. Revised editions of the same publication also require a new ISBN.

Fundamentals and Requirements


All forms of books are eligible for an ISBN, including educational books, maps and atlases, art and illustration books, and eBook applications. ISBN numbers are necessary for all publications, whether digital or physical. ISBNs are also issued to cassettes, CDs, and DVDs with content that is textual or educational in nature. 

Typically, the ISBN is printed on the lower portion of the back cover of a book, just above the bar code. When the publication is digital, the ISBN must also appear on the title screen, i.e., the first display page or the page that displays the title. In case of educational or instructional content, the ISBN must appear in the credit titles, whether at the beginning or the end. The ISBN must also be printed on the outside packaging of any given publication.

what is an ISBN: Breakdown

While some privately published books are released without an ISBN, the International ISBN Agency will attribute an ISBN to such books. Initially, a 9-digit SBN identification number was created in 1966. Later, a “0” digit was added to this number to give it an international standard. ISBNs were 10 digits long only until 2007. Today, ISBNs are 13 digits long. The ISBN is now divided into five parts with a hyphen, and includes a check digit at the end. 

  • Prefix:

All ISBNs since 2007 start with a prefix, also referred to as the European Article Number (EAN). This prefix is 3 digits long, and only 978 and 979 are currently used as prefixes for ISBNs. In the example shown below, 978 is the prefix.

What is an ISBN?

  • Group:

The registration group element can be 1 to 5 digits long. It represents the geographical or linguistic origin of the publication. For example, 0 or 1 is issued to English-speaking countries, 2 is issued to French speaking countries. Less frequently used languages usually have longer ISBNs. In the example below, the group code 81 represents India:

  • Publisher:

This element represents the individual printer or publisher that issues the book. The ISBN allocates a block of digits to each publisher. This block may be as long as 7 digits, depending on the size of the publisher. Larger publishers are usually allotted more digits, given their frequent publication needs, whereas smaller publishers are allotted fewer digits. In the example below, the publisher digits are 7525.

  • Title:

This element identifies the title of the book, and can be as long as 6 digits. A unique title number is assigned to each book and each edition of the book published by the same publisher. In the example shown below, 766 indicates the title:

  • Check Digit:

The check digit is the final single digit of the ISBN that is used to validate the rest of the ISBN. It is used as a form of redundancy check (an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data). In our example, 5 is the check digit.

Usage and Legal Implications

Although an ISBN is an international identifier, they are issued separately by organizations in each country. There are over 160 of these organizations in the world. Some organizations function under the government as national libraries, while some ISBN registration companies are funded by non-state organizations. These organizations can issue ISBNs to publishers. Most publishers acquire a unique publisher block from the ISBN issuing authority to represent themselves in the supply chain. Moreover, while an ISBN is merely an identifier and does not provide any legal protection (such as rights over intellectual property or copyright protection), some countries have made it illegal to publish books without having an ISBN allocated to them.

Content Writer @BooxAI
Ben Anderson is a content writer at BooxAI, he become known for his versatile writing and ability to engage readers. Ben’s content not only aligns with BooxAI’s mission but also brings fresh and diverse viewpoints, enriching the company’s narrative and outreach.