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Bar Codes And Lasers

[Universal Product Code graphic]

A beam of low intensity laser light is aimed at the Bar Code on your milk carton. The width and spacing of the lines is not accidental, but contains digital information. This digital code is scanned by a laser beam, and fed into the store's computer. The computer reads this code instantly, and sends the right information back to the checkout counter, about such things as the name, size, and price of the item.

Sometimes you will see a checkout person look at the barcode and type in some numbers. They are not reading the black and white lines, but a small sequence of tiny numbers next to the lines. This is the Universal Product Code. Bar codes sometimes store this information as well.