A GTIN is a ‘Global Trade Item Number’ – It’s an internationally known unique identifier for a product. When a GTIN is available, it will show next to the barcode on your product’s packaging. Submitting GTIN’s in your product data will help Google classify and display your products.
They’re 5 different types of GTIN’s, they vary in length depending on which type of product and where they will be sold.
UPC (North America) 12-digit number EAN (Europe) 13-digit Number JAN (Japan) 8 or 13-digit number ISBN (for books) 13-digit number ITF-14 (for multipacks) 14-digit number
Be aware not all products have a GTIN. If you can’t find the GTIN, you can contact the product manufacturer to ask for it.