ISBNtunnus

ISBNtunnus is the Finnish term for the International Standard Book Number (ISBN), a unique numeric identifier assigned to monographic publications. It is used worldwide to identify books and other book-like products, facilitating ordering, cataloguing, distribution and rights management across publishers, booksellers, libraries and digital platforms.

The ISBN system originated in the 1960s and is defined by the ISO standard ISO 2108. Modern ISBNs are 13 digits long (ISBN-13), beginning with a GS1 prefix (usually 978 or 979), followed by a group identifier (denoting language or country), a publisher or registrant element, a title element, and a final check digit. Older ISBNs used a 10-digit format (ISBN-10); ISBN-10s can be converted to ISBN-13 by prefixing 978 and recalculating the check digit. The ISBN-13 check digit is computed using a weighted modulus-10 algorithm; the ISBN-10 check digit used a modulus-11 system and could be the character X to represent ten.

ISBNs are allocated by national or regional ISBN agencies under the coordination of the International ISBN Agency. Publishers or self-publishing authors apply to their national agency to obtain single ISBNs or blocks of numbers. In Finland, allocation and guidance are provided by the National Library of Finland. ISBNs are frequently encoded as barcodes (EAN) on book covers to aid retail scanning and inventory control.