Global Tracking Identification Number or Global Trade Item Number. GTIN is the globally-unique EAN.UCC System identification number, or key, used for trade items (products and services) . It's used for uniquely identifying trade items (products and services) sold, delivered, warehoused, and billed throughout the retail and commercial distribution channels. Unlike a UPC number, which only provides information specific to a group of products, the GTIN gives each product its own specific identifying number, giving greater accuracy in tracking. Also see: EPC.