A standard barcode has two parts.
One part is the lines we usually noticed. It's nearly impossible to
decode using the human eye.
The other part is denoted in numbers, it is at the bottom of the
lines. The numbers desribes the product, e.g. manufacturer code and
product code. The cash registers are programmed with a database of
these numbers and its associated price.
Unless you are familiar with these numbers and its actual product,
it is also not possible to determine the price just by reading the
numbers.
