A barcode, also known as a universal product code (UPC), is a machine-readable form of information to be scanned on the surface of a product. The barcode is read by a scanner that transmits it into a database where it can be tracked. Each number on a barcode has a special meaning, and these numbers are added, multiplied and divided in some formula to give each of them their own uniqueness. Each barcode is composed of three segments.
The UCC company prefix (the manufacturer's number) number may consist of 6, 7, 8 or 9 digits. This number is assigned by the GSI-US. Generally, larger companies have longer numbers.
The item code (product number) is the number assigned to identify individual products and may consist of two to five digits (100 to 100,000 item codes). This number is assigned by the individual company.
The check digit is calculated from the company prefix and item code numbers, to ensure the data has been composed correctly.