UPC is a type of bar code, either UPC-A or UPC-E. UPC-A has a fixed length of 11 numerics 0-9 plus a checksum (with an optional 2 or 5 character extra set). UPC-E has a fixed length of 7 numerics 0-9 plus a checksum (with an optional 2 or 5 character extra set). So it depends what type of UPC barcode you are looking for information on. There are programs and/or fonts you can get to be able to reproduce barcodes on a printer.

|3lack|ce description on how the scanner interupts them is correct any scanner should read either versions of the UPC barcode.

This site is the home of the UPC org is http://www.uc-council.org/ may provide you with a little more info.

There are many other types of barcodes used for tracking such as Code 39 and I 2 of 5. Even the post office has their own bar code, PostNet, used for mailings.