More than five billion bar codes are scanned each day worldwide, and that number is increasing rapidly as the codes' uses extend beyond the checkout counter. Although bar codes are fast becoming ubiquitous, Norman Joseph Woodland, who patented the idea of a linear bar-code system in 1952, had to wait more than 20 years to see the system in action. His coinventor, Bernard Silver, didn't live to see it at all.

In 1948 the president of a grocery store chain in Philadelphia implored a dean at Drexel Institute of Technology to develop an automated checkout system. Silver, a graduate student, overheard the conversation and was instantly intrigued. Woodland, a friend and fellow grad student, shared Silver's enthusiasm, and the two devoted themselves to the effort. In late 1949 they applied to patent a system that drew on aspects of Morse code and movie sound systems. Similar to today's bar code scanners, their device used a light source and a photosensitive reader to translate data encoded in linear symbols. But because it required a blindingly bright, extremely hot 500-watt incandescent light bulb and a large, unwieldy vacuum-tube photomultiplier to process data, the invention wasn't appealing for widespread use in grocery stores.

The two inventors were undeterred. Their patent was granted in 1952, and Woodland hoped to continue to improve the system at IBM, where he had recently taken a job. The company expressed only  limited interest in Woodland and Silver's work, and after several years the two sold the patent to Philco and turned their attentions elsewhere. Silver died in 1962.

In the late 1960s just as Woodland and Silver's patent expired, several nascent technologies converged to make product-scanning systems feasible. The laser could provide an intense, low-heat light source, and processors were becoming small and inexpensive enough for commercial use. Several companies demonstrated prototype systems, causing quite a stir in the grocery industry. Ten grocery manufacturers and retailers formed a committee in 1970 to choose a standard for encoding product data.