Abarcodeis an optical machine-readablerepresentation of data relating to the object to which it is attached. Most of the barcodes are printed on the outside packaging of the objects, but for some products there are special labels to printed barcodes, which are called barcode labels. 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 into rectangles, dots, hexagonsand 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, In 1967, with the railway system maturing, Collins went to management looking for funding for a project to develop a black-and-white version of the code for other industries. Unfortunately they declined, saying that the railway project was large enough and they saw no need to branch out so quickly. Collins then quit Sylvania and formed Computer Identics Corporation. This company made some improvement of the entire process of barcodes which is much simpler and more reliable and can deal with damaged labels by reading the intact portions.

Barcodeswere not commercially successful until they were used to automate supermarket checkoutsystems, a task for which they have become almost universal. There is a unique barcode for each item in supermarkets, either printed on the packaging or small barcode labels. Their use has spread to many other tasks that are generically referred to as automatic identification and data capture(AIDC). In some small stores, price & barcode labels are printed and sticked to objests when they are chosen and weighed.