Are barcodes/UPC codes that are placed on food items and grocery store products centrally managed by the store they are purchased from or are they all unique identifiers to a specific product carried by a specific store and maintained by a third party?
As someone who has intimate knowledge of the second largest retailer in the world, I can tell you it's a mixture.<p>Basically you have food and non-food items. Food items that are weighed in-store for example can be given a barcode which starts with an in-store prefix, other food items contained in tins have a barcode that the manufactures have assigned following certain conventions (country of origin etc..) food created in-house gets yet another barcode because it may be produced from tinned food that is also sold on shelves. I could go on...<p>Non-food stuff tends to be packaged already and the barcodes are supplied by the manufacturer sometimes conforming to the recognised format sometimes based on their own product reference.<p>You can get software that generates a barcode depending on the information you want to encode, and it'll do it according to the recognised standards, but your data is your own.<p>The EAN Code is the most widely known code in Europe, but there are also Book codes ISBN and periodical codes... OK enough already!
Via Google - <a href="http://guides.wsj.com/small-business/starting-a-business/how-to-get-upc-codes-for-your-products-2/" rel="nofollow">http://guides.wsj.com/small-business/starting-a-business/how...</a>
An easy way to find out the answer would be to go purchase one thing from Store A and the same thing from Store B. You can rule out at least one possibility from there :)<p>I'll give you a hint, though: you can scan a barcode with your phone and compare prices :)