Bar code is a graphic identifier that arranges a number of black bars and blanks with different widths according to certain coding rules to represent a group of information. Common bar codes are parallel lines composed of black bars (referred to as bars) and white bars (referred to as spaces) with great differences in reflectivity.

Barcode can indicate the country of production, manufacturer, commodity name, production date, book classification number, starting and ending place, category and mailing date, and so on, so it has been widely used in many fields such as commodity circulation, book management, postal management, banking system and so on.

Bar code technology is an automatic identification technology developed in computer application, which is widely used in business, postal service, book management, warehousing, industrial production process control, transportation, packaging, distribution and other fields. It first appeared in the 1940s, and it is "composed of a set of regularly arranged bars, spaces and their corresponding characters, which are used to express certain information".

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Commodity barcodes include retail commodities, non-retail commodities, logistics units, location codes and barcodes. China has adopted the international commodity coding and barcode identification system, popularized and applied commodity barcodes, and established China's commodity identification system.

Retail goods refer to goods that are scanned and settled by POS machines at the retail end. Its bar code identification consists of the global trade item number and its corresponding bar code symbol. The barcode identification of retail goods mainly adopts EAN/UPC barcode. A can of beer, a bottle of shampoo and a bottle of conditioner can all be sold as retail goods to end consumers.

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