Barcodes are symbols that encode data. The data in the Universal Product Code or U.P.C. barcode is encoded in the bars and spaces in a very specific way. There are three elements to this “data string” in U.P.C. barcodes:

• A company prefix – is 6 to 9 digits in length and is a form of the globally unique GS1 Company Prefix assigned to your company by GS1 US. This U.P.C. Company Prefix ensures that your product’s barcode is not confused with another company’s product.
• An item reference – the item reference number is assigned by your company, based on a specific numbering system you have created for your products. The U.P.C. Company Prefix plus the item reference number form the first 11 digits of the U.P.C.
• A check digit – a special formula using those first 11 digits (the U.P.C. Company Prefix and the item reference number your company has selected) is used to calculate the check digit. This 12th digit ensures the accuracy of the information in your barcode when it is scanned.