Global Trade Item Numbers (GTINs) are a globally unique product identifier used to distinguish any trade item that can be priced, ordered, or invoiced in the supply chain. It is part of the GS1 system of international standards and is used worldwide to ensure accurate product identification in retail, e‑commerce, logistics, and inventory management.

GTINs are the numeric codes embedded in UPCs, EANs, and other GS1 barcodes, making them essential for scanning, tracking, and listing products across all platforms (Amazon, Walmart, Google Shopping, POS systems, etc.). 

• GTIN-8, 8-digit code, used for very small items where larger barcodes cannot fit
• GTIN-12, 12-digit code, the underlying data encoded in UPC barcodes used for POS scanning in North America (both UPC-A and -C)
• GTIN-13, 13-digit code, this is the most commonly used global retail barcode
• GTIN-14, 14-digit code, used for Case‑level / carton‑level / trade item grouping identification, Inner packs, multipacks, cases, and pallets (not intended for POS)