How do you make your own bar code?

A barcode is an optical machine-readable representation of data relating to the object to which it is attached. Originally barcodes systematically represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or one-dimensional (1D). Later they evolved into rectangles, dots, hexagons and other geometric patterns in two dimensions (2D). Although 2D systems use a variety of symbols, they are generally referred to as barcodes as well. Barcodes originally were scanned by special optical scanners called barcode readers. Later, scanners and interpretive software became available on devices including desktop printers and smartphones. The first step toward today's bar codes came in 1948, when Bernard Silver, a graduate student, overheard a conversation in the halls of Philadelphia's Drexel Institute of Technology. The president of a food chain was pleading with one of the deans to undertake research on capturing product information automatically at checkout. In 1951 Woodland got a job at IBM, where he hoped his scheme would flourish. The following year he and Silver set out to build the first actual bar code reader - in the living room of Woodland's house in Binghamton, New York. The device was the size of a desk and had to be wrapped in black oilcloth to keep out ambient light. It relied on two key elements: a five-hundred-watt incandescent bulb as the light source and an RCA935 photo-multiplier tube, designed for movie sound systems, as the reader.

Woodland hooked the 935 tube up to an oscilloscope. Then he moved a piece of paper marked with lines across a thin beam emanating from the light source. The reflected beam was aimed at the tube. At one point the heat from the powerful bulb set the paper smoldering. Nonetheless, Woodland got what he wanted. As the paper moved, the signal on the oscilloscope jumped. He and Silver had created a device that could electronically read printed material.