What Is a Barcode and How Do I Read One?

Find out what all those beeps at the cash register mean

Since barcodes were invented in 1952 by Bernard Silver and Norman Joseph Woodland, the technology has evolved along with digital technology. Today, various types of barcodes track and process all kinds of data. Here's a brief look at how barcodes work, how to read them, where to look up barcode data, and the various types of barcodes currently used.

Barcode on an item being scanned at a checkout register
katleho Seisa / Getty Images

Where Are Barcodes Used?

Barcodes are used for tracking information across a wide range of industries, most notably in product sales, travel, and food. Here are some examples of how barcodes are used:

  • Tracking parcels and envelopes sent in the mail.
  • Checking in passengers and luggage on planes, buses, and trains.
  • Keeping stock of store inventory.
  • Registering store or club membership cards.
  • Storing a website address or contact information.
  • Storing bitcoin or another cryptocurrency.

How Do Barcodes Work?

Barcodes work by representing numbers, letters, or special characters with deliberately spaced vertical lines that can be interpreted by a barcode reader device or a smartphone with a compatible barcode scanning app. Newer barcode formats, such as QR codes, are square and feature more complex coding that resembles pixel artwork.

To scan a barcode correctly, you'll need to have a device that can scan the code and a system that can interpret and read its data.

For example, if you're in a store, a clerk would use the store's barcode scanner to generate an item's information, such as its name and price. The store's scanner is set to interpret a specific barcode format (possibly a UPC barcode), and it's connected to a product database represented by those specific barcodes.

If you used that store's barcode scanner on a book's ISBN barcode, you'd likely get an error, because that device isn't set up to read ISBN barcodes and isn't attached to the right database to help it interpret any information.

Using the wrong scanner on a barcode is like trying to call someone on the phone with their ZIP code. Every system has its own set of numbers and codes.

What Are One- and Two-Dimensional Barcodes?

There are two main categories for barcodes: one-dimensional and two-dimensional.

One-dimensional barcodes are first-generation barcodes. They store information by using vertical black-and-white lines of varying length and thickness. ISBN, UPC, EAN, and Code 39 codes are all one-dimensional barcodes.

Two-dimensional barcodes, also referred to as matrix code or 2D code, are newer. 2D codes are typically square and can store more data than 1D codes. QR code, Aztec code, Data Matrix, and AR code are all two-dimensional barcode formats.

What Are the Most Popular Barcode Types?

There are numerous barcode formats used around the world in different industries, by different companies, and for different purposes. These are the three that you're most likely to encounter regularly:

QR Code

Quick Response code (QR code) barcodes can store a variety of data, from website addresses to personal or business contact information. They are two-dimensional barcodes that differ from the traditional black-and-white vertical line format. QR Codes are square, feature smaller squares within their upper-right, upper-left, and lower-left corners, and have what looks like pixelated artwork in their center. You'll often encounter QR codes on store windows and business cards.

QR barcode for data labeling
Douglas Sacha / Getty Images


International Standard Book Number (ISBN) barcodes are used to track books and ebooks globally. The vertical black-and-white-striped barcodes store the unique identification number assigned to a published book by an official affiliate of the International ISBN Agency. ISBN barcodes originally contained 10-digit numerical codes, but since 2007 they've evolved to incorporate 13.

ISBN code on a book
JLGutierrez / Getty Images


UPC stands for Universal Product Code. These barcodes, first used in 1974, are used globally for tracking products sold in online and physical stores. The UPC barcode format consists of 12 numbers represented by black-and-white vertical lines. These barcodes can only store numbers.

UPC Barcode

How to Read a Barcode With a Scanner

If you own a business, being able to read barcodes with a scanner is important. To get this process started, you'll need a barcode scanner. These are available from various online marketplaces, including Amazon. You'll also need a computer or laptop to connect to the scanner device and receive information from it.

Finally, you'll need a product database or software package to store your product information if you want to use barcode scanning to track products and orders. There are specialized software packages that perform these functions, including WASP, CMSStores, EZ OfficeInventory, or Orderhive.

How to Read a Barcode on iOS

You can turn your iPhone or iPad into a barcode scanner with the help of apps such as QR Code Reader-Barcode Maker, available from the App Store. This app can scan and make barcodes in more than 15 formats, including QR code, Barcode, Datamatrix, Code128, Code39, EAN-8, and EAN-13. Here's a quick look at how this app reads barcodes:

The iOS camera app features built-in QR code functionality. Open the app and position a QR code in front of your device. The camera app should scan the code and extract its information.

  1. Download and open QR Code Reader-Barcode Maker.

  2. Tap on the large circular barcode icon in the center of the screen.

  3. Tap OK to allow the app to access your camera.

    QR Code reader app accessing iOS camera
  4. Your device's camera will activate. Position a barcode within the camera's view, and the app will automatically extract information.

  5. If you've scanned a book's barcode, tap Search (magnifying glass).

  6. You'll be taken to a Google search results page about the book.

    Barcode scanner app reads a book's barcode
  7. If you've scanned a QR code, tap Search (magnifying glass).

  8. You'll be taken to a web page with the intended information.

    Barcode scanner reads a QR code and takes you to more information

How to Read a Barcode on Android

To scan a barcode on Android, you'll need to download an app such as Barcode Generator. This free app is designed for creating barcodes, but it can also read many barcode types.

  1. Open Barcode Generator on your Android smartphone or tablet.

  2. Tap Menu (three horizontal lines) in the top-left corner of the app.

  3. Tap Scan code.

  4. Your device's camera will activate from within the app. Place your barcode within the camera's line of sight.

    Your Android device's camera must be able to focus on text or images within a very close range. Cameras on some inexpensive Android tablets and phones may not be able to scan a barcode.

  5. Once detected, the app will extract any information contained within the barcode and display it on screen. The barcode will also be saved to the app's library for easy future access.

How to Look up an ISBN or UPC Number

It's easy to look up an ISBN or UPC barcode on one of the free services that specialize in this functionality. BarcodeLookup, for example, supports ISBN, UPC, and EAN barcodes and their related databases of registered products. The BarcodeLookup iOS and Android apps also let you scan barcodes directly via your device's camera.