The 57th anniversary of the invention of the bar code was honored by Google by greeting the Internet search engine users with a bar code in place of the usual Google logo.

Google honors 57th anniversary of the Bar code - Invention of the Bar code
In 1948 Bernard Silver, a graduate student at Drexel Institute of Technology in Philadelphia, overheard the president of a local food chain asking one of the deans to research a system to automatically read product information during checkout. Silver told his friend Norman Joseph Woodland about the request, and they started working on a variety of systems. Their first working system used ultraviolet ink, but this proved to fade and was fairly expensive.

Convinced that the system was workable with further development, Woodland quit his position at Drexel, moved into his father's apartment in Florida, and continued working on the system. He later decided that the system would work better if it were printed as a circle instead of a line, allowing it to be scanned in any direction.

On 20 October 1949 Woodland and Silver filed a patent application for "Classifying Apparatus and Method", in which they described both the linear and bullseye printing patterns, as well as the mechanical and electronic systems needed to read the code. The patent was issued on 7 October 1952 as US Patent 2,612,994.
However, bar codes were not used commercially until retailers in the National Association of Food Chains (NAFC) agreed on the familiar Universal Product Code designs that are still seen on billions of worldwide items today.

The first supermarket scanner that could read UPC bar codes was installed at a Marsh supermarket in Troy, Ohio, in June 1974. The first product to bear the bar code was a packet of Wrigley’s chewing gum.