Barcode is a graphic identifier that arranges multiple black bars and blanks with different widths according to certain coding rules to express a group of information. A common bar code is a parallel line pattern composed of black bars and white bars with different reflectivity.

Bar code can mark the country of production, manufacturer, commodity name, production date, book classification number, starting and ending place of mail, category, date and many other information, so it is widely used in many fields, such as commodity circulation, book management, postal management, banking system and so on.

Source: @tattoovasquez