Barcode

A barcode is simply a way of writing a number in a form a machine can read quickly and accurately. The pattern of bars and spaces (or, in 2D codes, squares) encodes digits that a scanner decodes in a fraction of a second. The barcode itself carries no inherent meaning — its value is entirely in the number it represents.

For retail products, that number is almost always a GTIN: a UPC in North America or an EAN in Europe. So when people talk about "getting a barcode" for a product, what they really need is a GTIN from GS1; the printed symbol is then generated from that number. The distinction matters because the same GTIN can be printed as different barcode symbologies without changing what product it identifies.

The two dominant retail symbologies are UPC-A, the 12-digit barcode used mainly in the US and Canada, and EAN-13, the 13-digit barcode used across Europe and most of the world. Both encode a GTIN. For very small packaging there is EAN-8, and for cartons and cases there is ITF-14, which encodes a GTIN-14.

Beyond linear (1D) barcodes, 2D codes such as QR codes and DataMatrix are increasingly used for packaging, traceability, and the emerging GS1 Digital Link standard, which can carry a GTIN alongside extra data like batch or expiry. But for the core job of identifying a retail product at checkout and on marketplaces, the 1D UPC and EAN symbols remain the standard.

To create legitimate retail barcodes, you first obtain GTINs by licensing a company prefix from GS1, then generate the barcode images from those numbers using barcode software or a GS1 tool. If you resell branded goods, the manufacturer's barcode is already on the packaging and you reuse it. If you make your own products, you need your own GS1 prefix so the numbers are registered to your brand.

Be cautious of cheap third-party "barcodes" sold online. The image is easy to generate — the value is in the underlying GTIN being properly registered to you. Amazon, Google and other platforms validate the encoded number against the GS1 database, so a visually perfect barcode whose number is unregistered or resold can still get your listing rejected.