All products must have a Universal ID, or Product Identifier, when they are created. This doesn't have to be a UPC - it can also be an EAN, ISBN, or ITF.
UPCs, or Universal Product Codes, follow a set of rules in order to be recognized and validated.
A typical process of obtaining a 12-digit UPC number is as follows:
- License a unique Company Prefix from your local GS1 office
- Assign product number(s) to unique products making your number equal 11 digits
- Using a check digit calculator with your 11 digit number, generate your check digit.
Combining the above steps will result in a 12-digit UPC number.
For more information about creating UPCs and obtaining a company code, see the GTIN.info website.
NOTE: The Vendor SKU is different than the Universal ID/Product Identifier