On January 1, 2007, the length of the International Standard Book Number (ISBN) officially changed from 10 to 13 digits. This change required book industry organizations to use 13-digit ISBNs instead of 10-digit ISBNs when identifying books in global trade. Pearson is began accommodating the use of 13-digit ISBNs in customer business transactions (e.g. inquiries, orders, returns) effective January 1, 2007.
Please visit http://www.pearsoned.com/isbn-13/index.html for more information.