How do Barcodes Work/

How Do Barcode Numbers Actually Work?

By Jake Wengroff

Each barcode contains a couple identifiers that provide two important pieces of information:

Which GS1 Organization the Barcode was purchased from: Company Prefix, which is the first six to nine digits; and
What the product is: Item Reference Number, which is the remaining numbers following the Company Prefix, not including the check digit. The last number is the check digit, which helps the computer read the barcode properly if another part of the barcode is read incorrectly.

Despite the fact that barcodes are used to relay information to computers when scanned, it’s important to note that the information is not stored in the barcode itself. The barcode is printed using laserjet, inkjet or thermal technologies and affixed to products and their packaging. There are no chips or sensors in the barcode itself.

So, how do barcodes actually work? Here’s a guide into how barcodes are formatted and the technology behind how they work.

How Barcodes Are Formatted

A barcode uses a very specific type of image to encode information. Barcode symbology refers to how the image or design is formatted, so as to encode information. 

The spacing and pattern of the black and white lines might seem to be random, but they are not: they follow standardized code languages established by the International Organization for Standards (ISO).

A barcode scanner will then read those images, detect the code, and then translate the information into a line of text that can be understood by a point of sale or inventory system. 

One-dimensional (1D) or linear barcodes are perhaps the most recognizable type of barcode. These labels use the classic black and white parallel lines and spacing to encode data.

Two-dimensional (2D) barcodes are newer and represent data with the use of squares or rectangles that contain black and white dots in specific patterns called a data matrix.

UPC Code as a Unique Identifier

When a cash register scans a barcode at the point of sale, the scanner is reading the UPC code and immediately looking up that number in the retailer’s point-of-sale system and inventory management system. Oftentimes, these systems are one and the same.
From there, the point of sale or warehouse system can display the associated product name, description, price, size or other information stored in the database. As a single identifying number, the UPC code makes it possible for systems to store large amounts of data about a product. 

Different retailers may identify or classify your product differently according to their own conventions. When you give a stockist a UPC code for one of your products, they will enter your product into their system with their own name, price, description, and other information. However, all of this information is still tied to your unique UPC code so you can track your products’ performance across retailers and channels.

The Technology Behind It

Today’s 1D barcode is read using a scanner. This scanner applies a laser to detect the pattern on the barcode label. 

During the scanning process, when the laser of a particular frequency sweeps across the barcode, some of the light is absorbed, while the rest is reflected. This is the reason for the use of black and white: the black lines are absorbed, and the white spaces are reflected.

The scanner detects the amount of light, which is then translated into a set of digits, or data. Using the set of numbers, information can be retrieved from a database.

Each element of a 1D barcode (1 digit in barcode language) is divided into 7 vertical modules, which consist of individual bars and spaces. Unbeknownst to many,  there are actually 95 evenly-spaced columns on each barcode, all with separate detailed data. These groups are interpreted by the computer as 1 digit only. For example, the number 1 is actually 0011001 (or a series of spaces and bars).

Barcode types vary by format. UPC codes are generally restricted to around 20 alpha-numerical characters. Any more than that would need a QR (2D Barcode) code.

However, what about those numbers underneath the black vertical lines? Do those matter in the scanning of a barcode label?  Oddly enough, the numbers printed underneath merely serve as a back-up in the event there are technical issues with the scanner. 

Ready to Make a Barcode Purchase?

Now that you have a better idea of how barcodes work, you may be ready to make a barcode purchase to sell you products on and offline. Bar Codes Talk provides barcodes to fit your every need, make a purchase today!

Have more barcode questions? Check out our support page.

Jake Wengroff writes about technology and financial services. A former technology reporter for CBS Radio, Jake covers such topics as security, mobility, e-commerce and IoT.

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