A Global Trade Item Number is a GS1 identifier used to identify a trade item, such as a product or a defined packaging level.
How it works in retail
GTINs support consistent identification across trading partners. They can be represented in appropriate barcodes or other data carriers, subject to GS1 standards.
A retail example
A brand assigns a GTIN to a packaged product so retailers can identify that trade item in their systems.
What to keep in mind
The GTIN is the identifier, while a barcode is a way to encode it. A retailer’s internal SKU serves a different identification purpose.
Sources & further reading
GS1: Identification keys reference
Examples are illustrative. Terminology and measurement conventions can vary by business and market.