A–Z barcode terms
This glossary covers the most common terms you’ll encounter when buying, printing, or validating barcodes. Definitions are kept concise with links to deeper articles where available.
Barcode
A machine-readable representation of data, typically shown as parallel lines (1D) or a matrix of dots/squares (2D). The pattern encodes numbers or characters that scanners decode into usable information.
Check digit
The final digit of a GTIN or other barcode number, calculated from the preceding digits using a weighted sum algorithm. It catches most single-digit errors and transpositions during manual entry or scanning. See also check digit calculator.
EAN (European Article Number)
A retail barcode symbology used worldwide outside North America. The standard form is EAN-13 (13 digits). EAN-8 is a compressed version for small packages. EAN-13 and UPC-A are technically compatible—most modern scanners read both. See GTIN overview.
GS1
The international not-for-profit organisation that administers the GS1 system of standards, including GTIN allocation. GS1 operates through national member organisations. See GS1 overview for how GS1-issued GTINs compare to reseller-issued GTINs.
GS1-128
A symbology derived from Code 128 that encodes GS1 Application Identifier data such as batch numbers, expiry dates, and serial numbers. Commonly used on logistics labels and healthcare products. Requires GS1-128-specific start character (FNC1).
GTIN (Global Trade Item Number)
The umbrella term for retail product identifiers: GTIN-8, GTIN-12 (UPC), GTIN-13 (EAN), and GTIN-14 (ITF-14). A GTIN uniquely identifies a trade item at a specific packaging level. See GTIN overview.
ISBN (International Standard Book Number)
A 13-digit GTIN-13 assigned to books, administered by the International ISBN Agency and national agencies. Prior to 2007, ISBNs were 10 digits; they now incorporate the 978 or 979 prefix ISBN Users’ Manual. ISBNs are valid GTINs and scan as EAN-13 barcodes.
ISSN (International Standard Serial Number)
An 8-digit identifier for serial publications (magazines, journals). For barcode use, ISSNs are typically converted to GTIN-13 by adding a 977 prefix and check digit recalculation.
ITF-14 (Interleaved 2 of 5, 14-digit)
A 14-digit GTIN used on shipping cartons and outer cases. Encoded in the Interleaved 2 of 5 symbology, which only represents numeric data. Always includes a GTIN-14 indicator digit (1–8 for packaging levels, 9 for variable measure). The ITF-14 barcode itself does not carry a check digit—the 14th digit is the GTIN check digit.
Quiet zone
The mandatory blank margin on either side of a barcode where no printing occurs. Scanners need this space to distinguish the barcode from surrounding graphics. Minimum quiet zone widths vary by symbology; for EAN/UPC it’s typically 7–11 module widths. Inadequate quiet zones are a leading cause of scan failures GS1 UK, Barcoding: Getting It Right.
Reseller GTIN
A GTIN purchased from a barcode reseller rather than obtained through direct GS1 membership. Reseller GTINs are legitimate numbers drawn from GS1-prefix allocations acquired before 2002 or from authorised pools. They are valid GTINs under GS1 standards but are not tied to ongoing GS1 membership fees. See GS1 overview for a balanced comparison.
Symbology
The specific encoding scheme that defines how data is represented in a barcode pattern. Each symbology has rules for character set, density, error detection, and physical dimensions. Common retail symbologies include EAN/UPC, Code 128, and Interleaved 2 of 5.
UPC (Universal Product Code)
The retail barcode symbology standardised for North American use. UPC-A encodes 12 digits (GTIN-12); UPC-E is a compressed 6-digit version for small packages. UPC-A and EAN-13 share the same scanning compatibility—UPC-A is effectively a subset of EAN-13 with a leading zero.
Quick comparison: retail identifiers
| Term | Digits | Symbology | Typical use |
|---|---|---|---|
| UPC-A | 12 | EAN/UPC | North American retail |
| EAN-13 | 13 | EAN/UPC | Global retail |
| EAN-8 | 8 | EAN/UPC | Small packages |
| ITF-14 | 14 | Interleaved 2 of 5 | Shipping cases |
| ISBN-13 | 13 | EAN/UPC | Books |
| ISSN (barcoded) | 13 | EAN/UPC | Serial publications |
Validation and verification tools
- GTIN validator and check digit calculator — verify number structure and calculate missing check digits
- GS1 GTIN definition — official GS1 reference
- International Barcodes Network — 120+ member reseller sites worldwide
- IBN Verified — barcode verification resources
Notes for editors
When expanding this glossary, keep definitions under 75 words. Link first mention of a term to its dedicated article if one exists. Use [[path|label]] wikilinks for internal cross-references. Flag terms that need dedicated articles with {{stub}}.