What is an ISBN number? It’s an acronym for International Standard Book Number.

Not only does an ISBN number identify the author but the title, edition, and format. We don’t bother buying our own batch of numbers but use what Amazon provides for free.

Apparently, the legal requirements around ISBNs have become stricter.

Ever wonder why there is a discrepancy between your ebooks and your physical copy of the same book. Blame it on ISBNs. An ISBN costs money and many publishers who buy these numbers in batches don’t want to deal with spending money on small corrections to the book.

The Amazon sight states:

Paperback updates

Many paperback attributes are locked after publication because of ISBN requirements. They can’t be updated unless you unpublish and republish your paperback as a new title.

See https://www.isbn-international.org/content/what-isbn for more information.