GTIN stands for Global Trade Item Number and is a unique, internationally recognized identifier for retail products and trade items [1][2]. Managed by the global standards organization GS1, a GTIN is the numerical data encoded in or printed beneath a product's barcode [1][2][3]. It serves as a universal language allowing manufacturers, retailers, distributors, and e-commerce platforms to identify the same product consistently across different systems and countries.

In retail operations, GTINs perform several critical functions. At the point of sale, scanning a barcode retrieves the product's GTIN, which the system uses to look up pricing and inventory information instantly. For inventory management, GTINs enable businesses to track stock levels accurately across multiple locations and warehouses. Major e-commerce platforms including Amazon and Google require GTINs to ensure product listings are unique and to help customers find exactly what they are looking for [3].

There are four primary GTIN formats used in retail [1][2]. GTIN-12, a 12-digit number, is primarily used in North America and is often referred to as a UPC (Universal Product Code). GTIN-13, a 13-digit number, is used predominantly outside North America and is commonly known as an EAN (European Article Number). GTIN-8, an 8-digit format, is designed for very small products where a full-sized barcode will not fit. GTIN-14, a 14-digit number, identifies trade items at different packaging levels such as cases or pallets rather than individual consumer units.

Companies obtain a GS1 company prefix from their local GS1 member organization, which they then use to create GTINs for their trade items [1]. Each GTIN includes a check digit calculated using a standard modulo-10 algorithm to detect scanning errors and ensure data validity. Unlike a Stock Keeping Unit (SKU), which is an internal code created by a specific business, a GTIN remains the same for a product regardless of who is selling it, ensuring global uniqueness and preventing confusion in international trade.