A UPC is a 12 or 13 (EAN) digit number that can be found below the barcode on your CD, DVD or video game case. Note: sometimes the lead and ending numbers are
smaller than the other 10 numbers; these smaller numbers must also be entered so that the code entered is a total of 12 or 13 digits. Each individual 12 digit UPC or 13 digit EAN must be entered without spaces or dashes.
An ISBN is a 10 or 13 digit number that can usually be found on the back cover
of most books above the barcode. When you enter an ISBN, include all 0's and
an X if applicable. Occasionally, the ISBN is found elsewhere. Each individual
10 or 13 digit ISBN must be entered without spaces or dashes.