The kind of information stored in a product's bar code?

The different bars reflect the scanners light differently and a sensor in the scanner interprets the different reflections which it translates into a number. Usually the number is also printed under the barcode so if the scanner cannot read it an employee can type it in manually. The number is the code that the store's computers can look up which tells its price and other information about it to the computer, automatically adding it to the purchase. Bar codes are designed to speed up checkouts so that an employee does not have to type in 100 ten-digit numbers.