The ubiquitous bar code is printed on just about everything these days. In fact, I don't think you could retail items without a bar code- how would one check the item out of the store?
The origins of the bar code system are interesting; they of course started off being used on the sides of railroad cars. Railroad cars? Yep, railroad cars. They were used in an automated system where rail cars carried a steel plate on each side, and on that plate were individual bands of specific colors and patterns. See here:
http://www.nakina.net/other/aci/aci.html The plates were scanned by an automated system as the cars passed, and the data collected. The system was in use as early as the 1960's, which actually predates the microprocessor, but was eventually discarded due to the difficulty in reading dirty, damaged or even missing bar codes.
As to modern bar codes on things like consumer products, well that started with Wrigley's chewing gum, the very first mass produced item to carry a modern bar code- back in 1974, long before there was anything in the way of automated scanning systems to read it.
Brian