The ISBN is a 10-digit number that uniquely identifies books and book-like products published internationally. Each number identifies a unique edition of a publication, from one specific publisher; its purpose is to allow more efficient marketing of products by booksellers, libraries, universities, wholesalers and distributors.

ISBNs are given to printed books and pamphlets, book readings on cassettes, microform publications and microcomputer software. ISBNs are not given to ephemeral material (such as diaries, calendars, theatre programs), sheet music, art prints and art folders, and serial publications such as newspapers, magazines and annual reports. Serial publications receive an ISSN – International Standard Serial Number. http://www.thorpe.com.au/isbn/