Take the barcode 69369838000 13 as an example.

This bar code is divided into four parts, from left to right: 1-3 digits: * * * 3 digits, corresponding to bar code 693, which is one of China's national codes. (690-695 are all codes of Chinese mainland, which are used internationally).

4-8 digits: **5 digits, corresponding to the barcode of 69838, representing the manufacturer's code, which is applied by the manufacturer and allocated by the state.

9- 12 digits: * * * 4 digits, corresponding to barcode 000 1, representing the commodity code in the factory, which is determined by the manufacturer.

13: * * *1,corresponding to 3 of the barcode, is a check code, which is calculated by the previous 12 bits according to a certain algorithm.

Extended data:

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".

Baidu encyclopedia-barcode