UPC barcodes are machine-readable versions of the Universal Product Code used to identify merchandise in retail stores. The barcode is scanned by a barcode reader to help automate checkout and inventory control procedures.
Universal Product Code barcodes are machine-readable translations of the numeric Universal Product Code listed at the bottom of the barcode itself. The varied thicknesses of the black lines in the barcode allow for a barcode reader to interpret the numeric code by bouncing a laser off of the barcode. Differences in the reflectivity of the dark and light areas are translated by the barcode reader into the corresponding numbers for lookup in a product database.
Every product with a UPC barcode is assigned a unique Universal Product Code. This code is formed by the combination of the manufacturer number assigned to the product's manufacturer by the Uniform Code Council and an item number assigned to the product by the manufacturer itself. Standard UPC codes are 12 digits in length, with the first six digits comprising the manufacturer number and the next five the item number. The last digit is reserved for the check digit, a number that allows a barcode scanner to verify that it has scanned a UPC code correctly.