A product identifier is a unique code or number assigned to a specific product to distinguish it from other products. Common examples of product identifiers include the Global Trade Item Number (GTIN), Stock Keeping Unit (SKU), and Manufacturer Part Number (MPN).
On a physical product, the product identifier is typically printed alongside a barcode to make it easy to scan and add the information to the point-of-sale system. They are also displayed in a series of numerical or alphanumerical digits, depending on the type of product identifier used. For example, for a Bluetooth speaker, its GTIN can be listed as 8765432109876, while its MPN can be listed as SPK-MNO456.