A barcode is an optical, machine-readable, representation of data; the data usually describes something about the object that carries the barcode.Originally barcodes systematically represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or one-dimensional (1D).
Later applications software became available for devices that could read images, such as smartphones with cameras.
An early use of one type of barcode in an industrial context was sponsored by the Association of American Railroads in the late 1960s.
Developed by General Telephone and Electronics (GTE) and called Kar Trak ACI (Automatic Car Identification), this scheme involved placing colored stripes in various combinations on steel plates which were affixed to the sides of railroad rolling stock.
Two plates were used per car, one on each side, with the arrangement of the colored stripes encoding information such as ownership, type of equipment, and identification number.
Barcodes became commercially successful when they were used to automate supermarket checkout systems, a task for which they have become almost universal.
Their use has spread to many other tasks that are generically referred to as automatic identification and data capture (AIDC).
The very first scanning of the now ubiquitous Universal Product Code (UPC) barcode was on a pack of Wrigley Company chewing gum in June 1974.
Other systems have made inroads in the AIDC market, but the simplicity, universality and low cost of barcodes has limited the role of these other systems until technologies such as radio frequency identification (RFID) became available after 2000.
In 1948 Bernard Silver, a graduate student at Drexel Institute of Technology in Philadelphia, Pennsylvania, US overheard the president of the local food chain, Food Fair, asking one of the deans to research a system to automatically read product information during checkout.
Silver told his friend Norman Joseph Woodland about the request, and they started working on a variety of systems.
Their first working system used ultraviolet ink, but the ink faded too easily and was rather expensive.