A GTIN (Global Trade Item Number) is a unique, internationally recognized product ID number of eight, twelve, thirteen or fourteen positions. The number of positions depends on the usage function of the number: articles, locations, shipping units or something else. After assigning, recording and sharing the meaning with trading partners, the meaning of the code is fixed.
The barcode is the most common appearance of the GTIN on the product packaging or book cover. A GTIN makes a product truly uniquely identifiable.