barcodes

Barcodes are machine-readable representations of data in the form of patterns of bars and spaces (1D) or two-dimensional patterns (2D). They encode identifiers for products, shipments, or assets and are read by optical scanners or cameras. Common 1D formats include UPC-A and EAN-13, Code 128, and Code 39. The 2D family includes QR codes, Data Matrix, and PDF417, which can store more data and support error correction.

Barcodes were developed in the mid-20th century, with the first commercial system introduced in the 1970s. The Universal Product Code (UPC) system, developed with industry groups, led to widespread use in retail. The first scanned UPC item occurred in 1974, a pack of gum.

Barcodes rely on standardized encoding schemes. In many regions, GS1 coordinates global standards such as UPC and EAN. A barcode's numeric digits include a check digit calculated using a modulus 10 algorithm to verify scans.

Formats differ in data capacity and use cases: 1D codes are compact and fast for simple identifiers, while 2D codes can embed URLs, routing data, or batch information. Barcodes are widely used in retail, logistics, healthcare, libraries, and event tickets.

Printing requires sufficient contrast and a quiet zone to withstand damage and misreads. Durability and placement considerations include label material, abrasion, and curvature, particularly on packaging or pallets.