UPC vs. SKU vs. PLU

Stores use many codes for inventory tracking. Here are a few you might have seen, but not sure how they are used.
A UPC, or Universal Product Code, is the number (usually under the barcode) universally used to identify a certain product. Identical products at different stores will have the same UPC. There are multiple UPCs. UPC10, UPC11, UPC12, and UPC14 are frequently used, with UPC12 being the most popular.
A SKU, or Stock Keeping Unit, is the product code used by an individual store. Many SKUs, for simplicity’s sake, were simply their UPCs, but most store-brand items have shorter SKU numbers. If a product’s packaging changes there might be two different UPCs represented by one SKU, because the newer item would eventually replace the older one.

A PLU is a Price (or Product) Look-Up. Some are universal, such as 4011 for bananas and some can be assigned by the store for unique items. Items with a PLU are generally sold by weight, or volume, or quantity. An item sold with a PLU could have 3 different numbers to represent its price, UPC, and the store’s stock keeping unit.