The Wall Street Journal says that GS1 US, a non-profit that sets standards for international commerce and trade, gives UPC codes to products. This means that a product bought at Wal-Mart or another store would have the same UPC code no matter where it was bought. You can look up UPC codes online at sites like UPC Database or scan them with apps like Barcode Scanner, which you can get from iTunes or Google Play. UPC codes have between 8 and 13 numbers.
As of 2015, Wal-Mart uses EPCs, or electronic product codes, which are like the bar code’s next generation. Wal-corporate Mart’s website says that EPCs work the same way as UPCs, but they also work through radio-frequency identification, or RFID.