Barcode types: EAN, UPC, Code 128 and Data Matrix

EAN-13 consists of a GS1 prefix, an item reference and a check digit. UPC-A and UPC-E are the North American variants, EAN-8 the compact form for small packs. All of them carry a GTIN, a globally unique trade item number. ISBN-13 is formally an EAN-13 with prefix 978 or 979.

The check digit is not decoration. It is computed with a weighted modulo-10 procedure from the other digits. A mismatch means the number was printed or generated incorrectly — a critical hint for self-made labels.

Code 128 can carry the full ASCII set and therefore appears on shipping labels. GS1-128 is Code 128 with application identifiers, such as (00) for the SSCC consignment number. ITF-14 is the robust linear code printed on corrugated cartons.

The distinction matters when scanning: an SSCC is not a GTIN. Copying numbers without context creates inventory errors. A good scanner labels the format and the identifier structure.

Data Matrix dominates industry because it packs high density into small areas and includes error correction. Aztec is common in ticketing, PDF417 on identity and shipping documents. Combined with GS1, these codes carry batch, expiry and serial numbers.

For printing: respect the quiet zone, secure contrast and match module size to scan distance. A Data Matrix with 0.2 mm modules works on a 30 cm label but not on a 10 mm nameplate.