GTIN
Also known as: Global Trade Item Number
A GTIN (Global Trade Item Number) is the umbrella GS1 standard for product identifiers — UPC, EAN, and ISBN are all specific lengths of GTIN.
The GTIN (Global Trade Item Number) is the GS1 framework that unifies retail barcodes worldwide. It is not a separate barcode you print but the underlying numbering standard; the UPC-A (12 digits), EAN-13 (13 digits), and ISBN (books) are all GTIN formats. Amazon's listing forms often label the external-identifier field "GTIN" to accept any of them.
Every legitimate GTIN traces back to a GS1 company prefix licensed to a specific brand owner. Amazon runs a GTIN-validity check against the GS1 database when you create listings, rejecting codes that are invalid, reused across unrelated products, or registered to a different company than your brand. Buying cheap, unauthorized "recycled" UPCs is a frequent cause of listing suppression.
For brand owners, Amazon offers a GTIN exemption for products that genuinely have no manufacturer barcode (e.g., handmade or bundle/multipack listings), letting you list without supplying a GTIN.
A seller's listing is suppressed for an "invalid product identifier." The UPC they bought from a reseller fails Amazon's GS1 GTIN check; they purchase a GS1-issued code registered to their own brand prefix and the listing is restored.