An ISBN (International Standard Book Number) is a controlled, 10- or 13-digit identification number allowing publishers, libraries, and book dealers to locate books. If you received an ISBN from Lulu the ISBN will include Lulu's prefix and Lulu will be listed as the publisher of record. If you assigned an ISBN that you own to the project, your publisher info will be listed. For more information on the history and purpose of ISBNs, see http://www.isbn.org.
An ISBN is not needed to publish on Lulu (Lulu ISBNs are available for free in the Lulu Publishing Wizard). An ISBN is needed to have a book distributed outside of Lulu and entered into the book industry commerce chain. Each version of a book — paperback, hardcover, second edition — must have a different ISBN. A unique ISBN distinguishes between different versions of a book, helping customers to be sure that they are ordering the book they want. For information on how to obtain an ISBN, see the How to get an ISBN for a book.
