Bar code is a computer code that uses a printed strip of parallel bars of different widths attached to commercial articles, identification cards, and postal mail to identify specific products, persons, or locations. The bars are usually black on a white background, and their width and number vary depending on the application. They represent the binary digits 0 and 1, sequences of which represent decimal numerals, letters, and other information.

The bar code system consists of the bar code itself in conjunction with a scanner-type device for reading the code strips and a computer for interpreting the output of the scanner. To scan a bar code into the computer, a handheld scanner or bar code pen is moved across the code strip or the code strip is moved across a stationary scanner built into a checkout counter or other surface. A computer reads the presence or absence of...