A QR Code is a 2d barcode (square matrix code) designed by the Japanese corporation Denso-Wave in 1994. Initially they were use to track automobile parts during the manufacturing process. Today they are ISO standardized and open source.

QR is an abbreviation for Quick Response. It is a two-dimensional barcode (matrix barcode) that can store a link, plain text, SMS text message, addresses, URLs, Geo location, e-mail, phone numbers, contact information and it is used for quick connections (response) between static and online content. They can be scanned with smart phone cameras using the appropriate QR Code reader (scanner). The easiest way to understand their nature in today's media world is to describe them as paper-based hyperlinks and this is a good description of what they do.

What are all the squares?

Quiet Zone or Margin: is used to isolate the code from other packaging information. This zone is four modules wide

Position Detection Patterns: located in three of the four corners. This allows 360 degree (omni-directional) high-speed reading of the code

Alignment Pattern: they can appear In more complex QR Codes and they will be located in the lower right hand corner. This pattern allows the QR reader to correct for distortion when the code is bent or curved.The number of alignment patterns used depends upon how much information is being encoded and appear on Version 2 and higher

Format Info: It contains the error correction rate and mask pattern of QR Code. The format information is read first when the code is decoded

Version Info: Span from Version 1 (21 x 21 modules) to Version 40 (177 x 177 modules)

Data Area: is an array of rows and columns. Each cell is stored as a binary number (1 and 0). Error correction codes are inserted into this area as well

Error-Correction: is applied to restore the data when a part of QR Code is missing. The restoration rate varies on 4 different error correcting levels. For example, if a damaged area is up to 15% of the entire code size, its data can be restored by level M error correcting

Timing Pattern: helps to detect the position of each cell in the QR Code

1. Contact Information and vCard: QR codes can contain contact information so someone can easily scan a QR code, view your contact details, and add you on their phone. You can input your name, phone number, e-mail, address, website, memo, and more. I've commonly seen these used on business cards, for instance. You give someone a business card, they see a QR code on the back, scan it with their phone, and easily add your contact info to their phone.
2. Calendar Event: If you have an event you want to promote, you can create a QR code containing info for that event. QR codes containing event info can contain event title, start and end date/time, time zone, location, and description. This could work well on an event flyer or possibly even on a website promoting.
3. E-mail Address: A QR code can contain your e-mail address so someone can scan the code, see your e-mail, and then open an e-mail on their phones. If your call to action is mostly to have someone e-mail you, this would be great.
4. Phone Number: Maybe e-mail isn't immediate enough and you want someone to call. Link it to a phone number.
5. Geo Location: If you have an event you want to promote, you might want to stick a QR code linking someone to a maps location. This will allow someone to scan your QR code and get directions so they don't have to manually type in an address.
6. SMS: QR codes can populate a text message with a number and message. You can have your QR code send you a text saying, "Tell me more about ABC," for instance.
7. Text: You can also just have a sentence or a paragraph of text. This could be fun for having some type of QR code based scavenger hunt where you can leave hints in QR codes.
8. WiFi Network: Set th QR Code up so someone can scan a the code and automatically configure wifi on their phones.
9. URL: You can use a link that takes someone to your Facebook fan page or Twitter profile. You can also link someone to a YouTube video. Or maybe you want someone to pay for something via PayPal.

Using free scan codes may result in costly and embarrassing mistakes for you and your company.

1. Dynamic Versus Static Scan Codes: with paid scan codes, you can change the URL after the scan code has been generated. For example, if you are promoting a television series, you may want to change the URL that the scan code points to for this week's teaser video. With free scan codes (jargon alert: "non-managed" or "direct code generation"), the information is contained in the scan code rather than pointing to a dynamic look-up table in a database that can easily be updated with the appropriate URL.
2. Early Production Deadlines: with paid scan codes, you can generate the code well before your content is ready. For example, if you have an early production deadline for a magazine ad, but the video you would like your scan code to point to will not be ready until after you need to provide your ad, then a paid scan code will make this – easier!
3. Correction: with paid scan codes, if someone makes a mistake regarding the URL that the scan code points to, you can easily make the correction: with free codes that's very hard to do unless you get a Ph.D. in engineering and scan codes and chocolate chip cookies for the IT guy to generate free codes using referring links). If you are already a rocket scientist in scan code generation, then you already know not to use free code generators because they will bite you in the tush.
4. Analytics: with paid scan codes, you can get analytics, including: total scans; unique users; gender; income; age; handset operating system; and scan location (including interactive maps); to help you make decisions about the effectiveness of your print advertising, for example.
5. Free Codes May Be Harder To Scan: free scan codes may be harder to scan because they often are "dense" compared to paid scan codes. That's because with free scan codes, the URL (or other information) is contained within the scan code rather than simply pointing to a dynamic look-up table in a database for the appropriate URL or other action.
6. Add Value: It's essential to add value to the scanning engagement experience. With paid scan codes, you can change the URL after the scan code has been generated, which may be key to creating value for the scanning experience. You may not know what works best for you until after the scan code is in use. For example, if you using the scan code to point to a product page on your website and you discontinue the product, you can simply change the URL.
7. Printing: Can you afford to toss large printing press runs because the scan code points to a URL that needs to be updated? When you use paid scan codes, you can easily update the URL for the scan code rather than reprinting brochures; catalogs; direct mail pieces; signage; or any other physical thing that contains your scan code such as t-shirts. For example, if you are a Realtor using a scan code on your Home For Sale signs, you'll want to change the URL that the scan code points to rather than printing up new signs for each Home For Sale sign.
8. Change: With paid scan codes, you can easily deal with change. For example, if you are using scan codes for vCard contact info for a direct mail piece and the contact info changes after the mailing goes out, you can easily change the vCard info.
9. Large Batch of Scan Codes: With paid scan code platforms, it's easier to generate a large batch of scan codes. If you need to create a large batch of scan codes with a free scan code generator, you – or your team – will likely be overwhelmed with the time-consuming code creation process. For example, while you may ultimately point to the same video, you may want to use different scan codes to know which print ads generated those scans.
10. Scan Code Management: With a paid scan code platform, it's easier to label and keep track of all your scan codes. That's important for making sure the correct scan code is used and for running scan code usage reports. For example, you may want to use different scan codes for different print ads and run a report that compares unique scan code usage by media. If you mark, track and manage campaign collateral for lead generation, you'll want to mark, track and manage your scan code campaigns too.

For most businesses, using free scan code generators will cost the business more: either eating the cost of re-printing, the inability to use the most effective value-added experience; or the time consumed using an inefficient free tool for volume business use.