What is an ISBN?

An ISBN, or International Standard Book Number, is a unique 13-digit number assigned to books or other media published internationally. It allows book sellers, libraries, universities and distributors to identify a specific book or edition of a book.

There are four parts to an ISBN. The first part is the group or country identifier, which identifies a geographic grouping of publishers. The second part is the publisher identifier, which denotes a specific publisher within the publisher group. The third part is the title identifier, which identifies the title itself or the edition of the title if applicable. Finally, the check digit is the validation check of the ISBN.