UPC Code - Universal Product Code, it’s universal for that product. A Wisdom Panel 3.0 Canine DNA Test is going to have that same UPC code whether it’s in Montana, or where you are in some other part of the country. It is UNIVERSAL.

UPC Codes need to be registered globally. You can register them with a company called GS1 that maintains the UPC database, or you can buy blocks of UPCs for dramatically cheaper through a company like Nationwide Barcode that will issue you a bunch of UPCs, plus there are others to choose from. But the key is, once you have a UPC, it is only used for that product and it is always printed on that product wherever it is.

FNSKU Code - Fulfillment Network Stock Keeping Unit. The FNSKU is the way that Amazon identifies a product that is unique to the seller that has sent it to the Amazon fulfillment center.

ASIN - Amazon Standard Identification Number.  It is made up of 10 characters comprising letters and numbers and is Amazon's own system for managing its huge catalog. Products other than books are given an ASIN number when they are first uploaded to Amazon. You can find the ASIN on the information page of a product under the Product Information section of the listing. Under the heading Additional Information, you will see the ASIN. You can also see the ASIN in the URL of a product.

ASINs are not always global. For example, a product listed on might have a different ASIN to the same product listed on the US version of the site,, or even In other words, ASINs are marketplace specific. For shoppers, ASINs improve the user experience whether they are browsing through categories or searching using the search box.

SKU - Stock Keeping Unit. This is mainly used for your own administration. You can pick any number / word combination. However, once you create the SKU in Amazon Seller Central you can’t change it anymore. We would advise people pick a SKU on which they can remember the product.

Comingled Inventory – It is logistically easier for Amazon to not keep your inventory separate from others that have the same UPC Code. When a buyer purchases that product from your Amazon listing, the fulfillment center takes any of the products to fulfill that purchase, but not necessarily yours.

Transshipment & Distributed Inventory Placement – Amazon has multiple fulfillment centers and may want your inventory split and shipped to different fulfillment centers. If we do not split your inventory for you, per Amazon’s instructions, Amazon will charge you to do that, and it will delay your inventory reaching any buyers.