UPC-A
UPC-A is the most common variety of UPC (Universal Product Code), at least in domestic USA usage. UPC is probably still the most commonly-encountered bar code in everyday life, though these days QR codes are catching up. Just about every product has one, and they are used at the checkout in most large stores to scan purchases into the cash register. UPCs were developed at IBM in the early 1970s and were in widespread use by the end of that decade. They are still in heavy use, though experts regard them as obsolete compared to newer bar code technologies which can encode larger amounts of information in a smaller size.
Another UPC format called UPC-E exists for use in more compact spaces.
EAN-13 is a slight variant that has 13 digits (instead of the 12 digits found on UPCs). The EAN-13 code is standard for all products sold outside the United States, and is used for some things such as books and medicines in the U.S. The 12-digit UPC is used on other US products.
Developer libraries
- ZBar bar code reader library: cross-platform
- zxing (Zebra Crossing) (barcode library for Java, ported to some other systems)
