UPC stands for “Universal Product Code.” It is a unique code assigned to products on Amazon. It helps to distinguish the product from the other items on the marketplace. Typically, the 12-digit UPC is printed as a barcode on the packaging or label of each SKU (Stock Keeping Unit).
Most categories on Amazon require a GTIN (Global Trade Identification Number), which can be UPC or EAN. These identifiers may vary with category. An SKU must have an EAN or UPC to list on the Amazon Marketplace. Once you create a product listing on Amazon, Amazon generates the ASIN, Amazon Standard Identification Number, a 10-character alphanumeric unique identifier. This unique identifier is used within the Amazon ecosystem.
https://www.sellerapp.com/blog/how-to-update-upc-on-amazon/
