What is a Barcode? 

A barcode is a printed symbol intended to be scanned, usually with a laser-based reading device (‘bar code scanner’). The symbol conveys data by the changes in the size and pattern of a sequence of non-alphabetic marks. Originally using simple lines of varying thicknesses, the symbols were first intended as a way to print Identifying Numbers in a highly reliable machine readable system way on cartons and labels for common consumer goods.(See UPC.)   The basic logic of the coding has been adapted and elaborated several times to create a wide range of machine readable codes for many industrial and consumer purposes.