What do the lines on a bar code mean?

Answer 1

As your in the Shopping section Ill explain the UPC barcode as its the most common

A bar code is a product descriptor code created to be read by a computerised scanner or EPOS machine ( a till). It consists of 11 numbers in groups of "0"s, the black strips and "1"s are the white strips. Tis is the format computers use - BINARY. A

The first number describes the type of product. Most products begin with a "0"; exceptions are variable weight products such as meat, cheese and vegetables (2), health-care products (3), bulk-discounted goods (4), and coupons (5).

The number 1 is never used as the scanner (a laser) could mistake it for a black bar - a 0

The next five numbers are the product's manufacturer. These are registered internationally to make the manufacture code unique. The next five numbers after that describe the product itself, including its color, weight, size, and other distinguishing characteristics. The code does not include the price of the item or any taxes to be added. When the identifying code is read, the information is sent to the store's computer database, this is frequesntly called the back office system, which checks it against a price list and returns the price to the cash register.

The last number is a check digit, which tells the scanner if there is an error in the other numbers. The preceding numbers, when added, multiplied, and subtracted in a certain way will equal this number. If they do not, a mistake exists somewhere.

Complicted at first but once you look at the codes on your food you will soon understand.

You will also see a in many codes now that they have become 14 charectors. This is because a 3 digit code as been added to the existing product information . GS1 Prefixes do not provide identification of country of origin for a given product. They simply provide number capacity to different countries for assignment from that location to companies who apply. Those companies in turn may manufacture products anywhere in the world.
lines on a bar code are almost like encrypted files, they can only be read or detected through a special device. This allows a computer (cash register) to acknowledge an item and decodes the price.