What does an ISBN number tell you?

An ISBN is essentially a product identifier used by publishers, booksellers, libraries, internet retailers and other supply chain participants for ordering, listing, sales records and stock control purposes. The ISBN identifies the registrant as well as the specific title, edition and format.

Does every book have an ISBN number?

Every book published has a unique number assigned to it – an International Standard Book Number (ISBN). … ISBNs can, however, identify books in all formats – audio and digital, as well as printed, for example.