A barcode is a machine-readable representation of data. In retail and logistics, that data is typically a product identifier—most commonly a GTIN (Global Trade Item Number)—that computers can read faster and more accurately than human-typed entry.
How barcodes work
A barcode encodes information (usually numbers and sometimes letters or URLs) into a pattern of lines, spaces, or dots. This pattern is known as the barcode symbology (or symbol). A scanner shines light on the pattern, measures the reflections, and converts the result back into the original data. In retail and logistics environments, the encoded value is often looked up in a database to retrieve product information such as price, description, or stock level.
Product identifier barcodes do not store detailed product data inside the symbol itself. They store an identifier that points to a record in a database. This distinction matters for small business owners choosing their first barcode system: After selecting a symbology to use, you need both the barcode image and a product identifier to encode into it, as well as a way to register or share the associated product data with trading partners and their databases.
1D barcodes: the classic retail formats
One-dimensional (1D) barcodes—also called linear barcodes—are the familiar patterns of vertical lines seen on nearly every consumer product. The most common formats (symbologies) for barcodes used in retail are:
| Format | Typical use | Digit length | Region |
|---|---|---|---|
| EAN-13 | Retail point-of-sale | 13 digits | Worldwide; standard outside North America |
| UPC-A | Retail point-of-sale | 12 digits | North America |
| ITF-14 | Shipping cartons, cases | 14 digits | Global supply chain |
| GS1-128 | Pallets, logistics, batch/lot data | Variable | Global supply chain |
EAN-13 and UPC-A are the most common retail barcode symbologies. Both encode a Global Trade Item Number and are functionally interchangeable in most modern scanning systems. A UPC-A barcode encodes a 12 digit GTIN. An EAN-13 barcode encodes a 13 digit GTIN. 13 digit GTINs beginning with a zero are equivalent to their 12 digit GTIN counterparts (The leading zero is padding which does not modify the GTIN). Adding a zero to the beginning of a 12 digit GTIN will convert it into a valid 13 digit GTIN. In this way the 12 digit GTINs encoded in UPC-A barcodes can also be encoded as EAN-13 barcodes by adding a adding a zero to make them 13 digits long. ITF-14 and GS1-128 are used on outer packaging and logistics units rather than individual consumer items.
For a deeper comparison of when to use each format, see Choosing a barcode type.
2D codes: QR codes and beyond
Two-dimensional (2D) barcodes store data in both horizontal and vertical dimensions, allowing much higher information density in a smaller space. The most ubiquitous 2D barcode is the QR code, which can encode arbitrary information such as URLs, contact details, or payment information readable by scanners, including smartphone cameras.
In supply chain contexts, GS1 Digital Link is a structured URL format used to encode a GTIN within a QR code or Data Matrix symbol. This lets a single barcode symbol serve multiple purposes: a scanner at checkout reads the GTIN encoded in the Digital Link for pricing, while a consumer’s smartphone can follow the embedded URL to access product information, sustainability data, or authentication services. GS1 maintains standards for 2D barcode adoption in healthcare, fresh foods, and general retail 1.
What GTINs identify (and what they don’t)
A GTIN (Global Trade Item Number) identifies a trade item—a product as it is bought or sold. This includes:
- The specific product variant (size, colour, flavour)
- The brand owner who assigned the number
- The packaging level (each, case, pallet)
What a GTIN does not tell you:
| GTIN does NOT indicate | Why it matters |
|---|---|
| Country of manufacture | The prefix does not guarantee origin; it shows where the number was issued 2 |
| Quality or authenticity | GTINs are identifiers, not certifications |
| Who currently owns the brand | Some GTINs, depending on who issued them, can be transferred or licensed between companies |
This is a common source of confusion. For example, a GTIN beginning with “93” (Australian prefix) means the number was originally allocated for use by GS1 Australia. It does not mean the product was made in Australia. The product may have been made overseas and packaged for retail in Australia. For more detail, see GTIN overview.
Getting started with barcodes
For small businesses and first-time buyers, the practical steps are:
- Determine how many products require a barcode — each unique product variant needs its own GTIN.
- Choose between GS1 membership or a barcode reseller — GS1 issues numbers directly in most countries; resellers offer numbers from existing pools of transferable numbers, often with faster turnaround and lower upfront cost for small catalogues. Both routes produce valid GTINs, however some retailers have specific barcode supplier requirements, requiring GTINs issued by GS1.
- Select the right barcode symbology/format — typically EAN-13 or UPC-A for retail items.
- Generate and test your barcode image — ensure it scans reliably at your intended print size.
You can verify any GTIN’s check digit using the GTIN validator, and check whether a product is already registered in public databases through Barcodes Database.
Further reading
- Choosing a barcode type — match formats to your use case
- GTIN overview — structure, prefixes, and assignment
- GS1 GTIN definition and rules
- GS1 US: What is a GTIN?
- International Barcodes Network — member reseller sites in 120+ countries
Footnotes
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GS1, “2D Barcodes” — https://www.gs1.org/standards/barcodes/2d-barcodes ↩
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GS1, “GTIN Management Standard” — https://www.gs1.org/standards/id-keys/gtin ↩