Basically a UPC code is a 12 digit codes that are displayed in two different ways. The first of its kind is the bar code which is designed to be read by the computer scanners. It contains alternate black and white bars of various widths. Each numeric starts from 0 to 9 with a specific pattern that you want to place as per your wish.
You need to consider both the white and black bars while deciphering the code. Basically the bar code starts and ends with black bar and white bar each one unit in a width.
These are commonly known as start code and end code between this start and end code you will find certain numbers that will be reflected in the bar codes. Basically these UPC codes are used in retail chains to identify the products.
The second parts of these UPC codes are commonly known as the plain text version that is basically printed near the bar code so that the cashier or any reporting person on duty can read it easily. These are basically alternative options used when the scanner is not working in a proper manner.
So in this way the bar code works and we provide you the code that best suits your needs in the right order.