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What is a QR code? How does it work and its applications

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  • 8 min read

QR Codes (Quick Response codes) are a set of two-dimensional barcodes that provide diverse information ranging from website addresses and links to videos and images. In a way, they simplify the process by eliminating the need for typing or searching the link, web address and other information which, in turn, attracts more people to the website or the business due to the ease of access. The simple implementation of the tech makes it easier to share the information that’s accessible to everyone who has a smartphone.

Developed by Denso Corporation in 1994 for tracking the automobiles during manufacturing, QR codes are now used to communicate almost any kind of information. A QR code is different from the barcode in a way that the QR code contains pixels (modules) instead of bars. For standardisation purposes, the information in a QR code is encoded according to ISO/IEC 18004:2015.

How to scan a QR code?

QR code contains an encoded piece of information that can be alphanumeric, numeric, binary and kanji. Kanji are Chinese characters that are used in Japanese writing. In addition to that, several other extensions are also used. Below is the QR code of Candid.Technology — you can scan this and will probably get a link to redirect to our website.

QR code for Candid.Technology | Made via

In several devices, especially those running stock Android, you can scan the above QR code with the regular camera app. However, in most cases, you will need a QR code scanner or Google Lens. You can download the scanners from marketplaces such as Google Play or iOS store. Some devices have the scanner pre-installed in them.

For scanning, open the camera or the scanner and line up the lens over the code. It will scan the code and will take you to our homepage.

Also read: How is RAM used in gaming and how much do you need?

What are the elements of a QR code?

Richard Wheeler (Zephyris) | Wikimedia Commons

QR codes encompass the following elements.

  • Version information: QR codes have version numbers, ranging from 6 to 40. If the version number is under 6, then there is no need for version information as the code will automatically work out the data itself.
  • Format information: Informs about the type of data stored. The information can be anything from a URL to an SMS message to an app download link, among others.
  • Data and Error correction information: The grey area on the image above represents the actual data in 8-bit code form alongwith error correction, which too is stored in 8-bit format.
  • Position: The three squares, one on the bottom left and two on upper right corners, are universal and will be present in every QR code that you will see. These are essentially the position markers that define the boundary of the code. These allow the QR scanner to recognise the QR code and also check the correct orientation.
  • Alignment pattern: It is useful when the image is moderately distorted.
  • Timing pattern: These are the black and white lines connecting the three alignment patterns and determine the width of each module.

What are the uses of a QR code?

Nicolas1981 | Wikimedia Commons

QR codes have gained acceptance in a wide variety of applications primarily because they’re easy to use and secure. Significant use of QR codes can be seen in:

  • Consumer Advertising
  • Tracking products (initially, they were designed for tracking vehicles)
  • Marketing (discounts are offered by scanning the code)
  • Business Cards
  • Generating tickets (railway tickets, film tickets, etc.)
  • Currencies (first used by Royal Dutch Mint in 2011)
  • QR Payments (for example Paytm and other mobile wallets)
  • Social Media (Whatsapp, Snapchat, Twitter, Instagram, Facebook Messanger all use QR codes in one way or the other)

Other than that, QR codes are used in WiFi and website login, to sending out e-invitations for events as well as in video games.

5 Types of QR code

QR codes are of five different types, which are as follows.

QR Code Model 1 and 2

This is the most widely used type. The maximum coding capacity of a Model 1 Qr code is 1167 numerals, and the maximum version is 14, which is 73 x 73 modules.

Model 2 is the upgraded version over Model 1 and can be read on curved or distorted surfaces. Model 2’s encoding capacity is 7089 numerals, and its maximum version is 40 (177 x 177 modules).

Micro QR code

It has only one position detection pattern, and that is why it can store a maximum of 35 numerals. However, it is more effective than a regular QR code.

Micro QR code has four different variations, from M1 to M4, each consisting of varying levels of data storage capacity. M1 has 11 x 11 modules and can store only five numeric characters. Whereas, M4 has 17x 17 modules and can save a maximum of 35 numeric, 21 alphanumerics, 15 binary and nine kanji characters.

iQR code

This code can store a wide range of data. Also, these are used in a wide range of application since they can be printed as a rectangular code or dot pattern code or black and white inversion code. iQR code can store 80% more information than the standard QR code with only 30% of the size (minimum size is 9 x 9), which can hold a maximum of 40,637 characters in its 422 x 422 module size.


SQRC are QR codes with additional restrictions on them. These are useful for communicating private information that one would like to keep secret. Unlike the previous codes, these are registered trademark of Denso Wave Incorporation. A cryptographic key is used to restrict the information so that only the select devices can read it. It eliminates the need for additional encryption or decryption software. These codes are useful in preventing forgery and protecting personal information.


These are the next generation QR codes and contain a canvas area inside the QR code where the company logos or the designs can be incorporated. These codes enhance product appeal. Apart from that, the codes prevent forgery and provide an idea about the QR code.

Also read: Is Chrome becoming a surveillance software for Google?

QR Code security concerns

QRLJacking: How scanning a wrong QR Code can compromise WhatsAppAs we have seen, QR codes are useful in all walks of life. However, using QR code poses certain risks too. Although the documented risks are low, it is worth mentioning them.

  • Malware Risks: Malicious programs can be encoded into QR codes. Malware can impose real security risks to the device. It is therefore advised that you maintain caution while scanning the code.
  • QRLJacking: An attacker can read the Whatsapp messages. A fake and malicious QR code is created for this purpose. You can read more about QRLjacking here.
  • QRishing: It means phishing utilising a QR code. QRishing is similar to phishing, but here, the bait is a QR code. The most common method of QRisihng involves advertising QR code as a discount voucher. The attacker can also paste malicious QR code on top of a real one, which was used in banks.
  • Spying via QR code: QR code can be used for spying and surveillance purposes. China has been using QR codes to track minorities.  QR codes are installed on the homes where the caders can check the codes. QR codes are also installed in certain knives to monitor them in the event of a crime.

As we have seen in the article, QR code, like all tech, have certain risks involved in them. QR codes should be used with caution as once the code is scanned, there is not much you can do. So, taking necessary cybersecurity precautions is the only key to secure yourself.

Also read: What is Formjacking, how it works and protective measures

Kumar Hemant

Kumar Hemant

Deputy Editor at Candid.Technology. Hemant writes at the intersection of tech and culture and has a keen interest in science, social issues and international relations. You can contact him here: