UPC codes are assigned to products from GS1 US, a non-profit that sets standards for international commerce and trade, reports the Wall Street Journal, and therefore a UPC code for a product purchased at Wal-Mart or another store would be the same number regardless of where it was purchased. UPC codes can be looked up online from databases such as UPC Database or can be scanned with applications such as Barcode Scanner, available through iTunes or Google Play. UPC codes are either 8, 12 or 13 digits long.
As of 2015, Wal-Mart uses EPCs or electronic product codes, which is the next generation of the bar code. EPCs work similarly to UPCs with the addition of working through radio-frequency identification or RFID, according to Wal-Mart's corporate website.