What are ISBNs? ISBNs are 10 or 13 digit codes identifying specific editions of a book. They're sometimes written with hyphens. Examples: 0321543254, 0-321-54325-4, 9780321543257.

ISBN codes are usually listed on a book's back cover, bar code, or copyright page.

Searching by ISBN ensures that you find the exact edition you are looking for when buying textbooks or selling textbooks.