ISBN is the acronym for International Standard Book Number. It's been in use worldwide since the early 1970s. They come in a 13-digit and 10-digit variant, but both numbers are associated with the same product. The 13-digit (starting with 978...) is usually best if available.
Where Can I Find These on BetterWorldBooks.com?
Every item has a Product Detail section under the overview tab
On a physical copy, this number can be found on:
-The back side of the title (or copyright) page
-The back of a dust jacket
-The back of a paperback
Typically a barcode is available, similar to the one below:
Most books published before 1970 do not have ISBNs. These titles are listed on our website with an internal inventory number created by our system (starting with BWB). This number can be used in place of an ISBN when searching on our website or contacting us about a book. These numbers will not be found in the book as described above.