June 26th, 2025

A barcode is an optical machine readable representation of data, which shows data about the object to which it attaches. Originally barcodes represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or one-dimensional (1D). Later they evolved intorectangles, dots, hexagons and other geometric patterns in two dimensions (2D). Although 2D systems use a variety of symbols, they are generally referred to as barcodes as well. Barcodes originally were scanned by special optical scanners called barcode readers; later, scanners and interpretive software became available on devices including desktop printers and smartphones

The first use of barcodes was to label railroad cars, but barcodes were not commercially successful until they were used to automate supermarket checkout  systems, a task for which they have become almost universal.