I understand that you need one for different types of the same book, such hardback, paperback, etc. But it seems that some have many ISBN's for the very same version (or type) of that book. A case in point is a book I have posted. (This is an honest question, so I will not mention the book...as I am not "advertising" it) There are over many people wishing for it, but it is not being held or automatically ordered, because MY ISBN is not one of the many on the wishlists. Yet, my book is the same as some of the others.  So why the different ISBN? This can be so frustrating on a site such as this. And this is not the only time I have seen this happen. Do they give the books a different ISBN when they are printed in different years? I really am curious about this.

Sometimes publishers reissue books and when they do so they reissue a new ISBN. This is not always the case, but this could be why your copy is not wish listed.

Sometimes people want  a certain version. If it's a reissue they may want the newer version or maybe they want an earlier version to add to a collection. However the case your book will be offered to these wishers via e-mail letting them know a similar version has been posted into the system. This of course only happens if they have this option turned on in their settings.

There is a thread in the Book Bazaar for wishlisted books with different ISBN's.  A lot of people find that's a good place to find "wishers."

Also, as Leslie said, if the system recognizes your book as a "similar book,"  it will send e-mails out to people who are wishing for another version (if they have that particular e-mail option enabled in their acct. settings) with a link to your posted book.

Thank you for answering this for me Leslie....I know my book will get ordered, but I really was curious about why there are so many different ISBN's for the same book. I guess I can understand someone wanting a newer book, but I still think it's a pain having so many numbers for the same thing. LOL.

I wondered this too and asked awhile back - the reply was that some books of course get different ISBNs for HC, PB and audio versions...and then more popular books also get a million different versions released like book club editions, mass market paperback edition, etc. 

There are also different ISBN's for British/Canadian/Australian editions - with different ones for each type of binding.

For the curious (or those that have trouble sleeping), here's a listing from the folks that assign ISBNs of the circumstances under which separate ISBNs should be assigned: http://www.isbn-international.org/en/userman/chapter5.html 

I am amused to note the last one, "ISBN can never be re-used".  I wish we could print that on a wet noodle and use it to thwapp the publishers that have done so, and in doing so caused PBS posting confusion :-)

Cheers,

Catt

Wow, thank you everyone. This has been most interesting. I do wish they would stick to just one ISBN per type though. Sure would make it easier...but I know.....that's like wishing I lived on the moon...heehee.