The UPC-E barcode is a Universal Product Code, the most widely used barcode in the United States. UPC-E is the condensed version of the standard sized UPC-A numeric barcode, used in grocery stores and other retail establishments across the country. The condensed version is used on smaller products whose packages don't have room to place the full sized UPC-A code.
Specifications: A UPC-E barcode is half the size of UPC-A, with 6 digits instead of 12. Other than that, the two codes are set up the same way, with a digit at the beginning to designate the type of product being scanned (regular product, coupon, weighted item, etc.) followed by a manufacturer's code, a product code, and, finally, a check digit to ensure accuracy. The reduced size of the UPC-E is because it omits all of the extra zeros that are normally found in a full sized code: i.e., the zeros that come before the product code and after the manufacturer's code.
Advantages: Its condensed size allows it to fit on smaller packages. It also has a check digit, to ensure accuracy when typing a code in by hand.
Disadvantages: It's only a numeric code and cannot encode letters. Additionally, the fixed length limits the amount of information that can be encoded, making it fine for supermarkets, but inadequate for communicating more detailed information.