Bar codes are widely used, from our life to industrial production, to food and drug safety and so on. For example, a computer has many bar codes, each accessory has a manufacturer's number, the whole machine also has an independent bar code, and the whole machine packaging also has one, which involves the traceability of product quality. If there is a quality problem, it can be traced back to the root cause of the person in charge and transported by packaging logistics. There are also electronic bank bills, hospital medical records, commodity codes and warehouse barcodes. As you said, those represent three fields respectively. Bar codes of auto parts are convenient for quality traceability and management, supermarket cashier and inventory management, and airport luggage and air tickets are actually a warehouse. Each piece of luggage is numbered for easy management, and can be automatically scanned and sorted after being connected with background data. Now almost all industries have applications.
It is not easy to type so many words. Contact me if you want to know more. I have been in the bar code industry for 5 years.