Question 1

Do I need a new ISBN if I am publishing a new edition of my book?

Accepted Answer

Yes. If you make substantial changes to the text, add a new foreword, or significantly alter the pagination, it is considered a new edition and requires a brand new ISBN. This ensures that a student trying to buy the revised 2nd edition for a class does not accidentally purchase the outdated 1st edition. However, simply fixing a few typos or changing the cover art on an existing edition does not require a new ISBN.

Question 2

Does a reprint of a book require a new ISBN?

Accepted Answer

No. A reprint is simply a new print run of the exact same edition. Because the text, format, and pagination have not changed, the ISBN remains exactly the same. The publisher is merely replenishing their physical stock.

Question 3

What does the letter 'X' mean at the end of an ISBN?

Accepted Answer

The letter 'X' is the Roman numeral for 10. Because the legacy ISBN-10 format uses a Modulo 11 mathematical algorithm, the result of the check digit calculation will sometimes be the number 10. To keep the ISBN strictly at 10 characters long, the 'X' is used instead of a double-digit '10'. This only occurs in ISBN-10s; an ISBN-13 will never contain an 'X'.

Question 4

Can an ISBN-13 starting with 979 be converted to an ISBN-10?

Accepted Answer

No, it is mathematically impossible. The ISBN-10 format only has enough capacity to map to the 978 prefix block. When the 979 prefix was introduced to expand global capacity, it broke backwards compatibility. A 979 ISBN-13 must remain a 13-digit number and cannot be shortened to 10 digits.

Question 5

Is obtaining an ISBN legally mandatory to publish a book?

Accepted Answer

No, there is no legal requirement to have an ISBN. You can print a book and sell it directly to customers at a conference or through your own website without one. However, if you want to sell your book through major retailers (like Amazon or Barnes & Noble), distribute it through wholesalers, or have it stocked in libraries, an ISBN is commercially mandatory as their supply chains cannot process products without one.

Question 6

Can two different books ever have the exact same ISBN?

Accepted Answer

Under the official rules of the International ISBN Agency, absolutely not. An ISBN is meant to be a unique global identifier forever. However, human error does occur, and occasionally a publisher will mistakenly assign the same ISBN to two different titles. While this violates the standard, it does happen in reality, creating significant cataloging headaches for libraries and retailers who must manually resolve the conflicting data.

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