GS1 is a neutral, international not-for-profit standards organization that develops and maintains global supply chain standards for the identification of products, locations, assets, documents, and services. Founded in 1977 and headquartered in Brussels, Belgium, GS1 operates through a network of 116 national member organizations (such as GS1 US, GS1 UK, GS1 Germany) that serve over 2 million member companies in 150 countries. GS1's most visible output is the barcode system used on virtually every consumer product sold globally—the UPC (Universal Product Code) in North America and EAN (International Article Number) worldwide—but GS1 standards extend far beyond barcodes to encompass RFID (EPC/RFID), data syntax (GS1-128 Application Identifiers), and digital product identifiers.

At the core of GS1 is the GTIN (Global Trade Item Number), a family of numeric identifiers that includes GTIN-14 (14 digits, for trade units at all packaging levels), GTIN-13 (EAN-13), GTIN-12 (UPC-A), and GTIN-8 (EAN-8). A GTIN uniquely identifies a specific product at a specific packaging level globally—no two different products from different companies share the same GTIN. GTINs are the key that connects physical products to digital product information in retailer databases, e-commerce platforms, and supply chain systems. GS1 also manages the SSCC (Serial Shipping Container Code, 18 digits) for uniquely identifying logistics units like pallets, and the GLN (Global Location Number, 13 digits) for identifying physical and legal entities like warehouses, stores, and companies.

GS1 Application Identifiers (AIs) are two- to four-digit codes prepended to data fields in GS1-128, GS1 DataMatrix, and GS1 QR Code barcodes to define the meaning of the data that follows. For example, AI (01) indicates a GTIN, AI (10) indicates a lot/batch number, AI (17) indicates an expiration date, and AI (21) indicates a serial number. These AIs enable a single barcode on a pharmaceutical package, food product, or medical device to carry a GTIN, lot number, expiration date, and serial number in a standardized, interoperable format that any GS1-compliant scanner and software system can parse correctly. GS1 compliance is mandatory for suppliers to Walmart, Amazon, Target, the FDA Drug Supply Chain Security Act (DSCSA), and the EU Falsified Medicines Directive (FMD), making GS1 membership and correct barcode implementation essential for most manufacturers and distributors.