Overview#Barcode is an optical, machine-readable, representation of data
Barcode the data usually describes something about the object that carries the Barcode.
Originally Barcode systematically represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or one-dimensional. Later two-dimensional (2D) codes were developed, using rectangles, dots, hexagons and other geometric patterns in two dimensions, usually called Barcode although they do not use bars as such.
Barcode originally were scanned by special optical scanners called Barcode readers. Later applications software became available for devices that could read images, such as smartphones with cameras.
Barcodes became commercially successful when they were used to automate supermarket checkout systems, a task for which they have become almost universal. Universal Product Code (UPC) is the "Standard" used for these activities.
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.