All About QR Codes: What Are They and What Is Their Use?

What is a QR code?

The QR code, short for “Quick Response Code”, is a type of two-dimensional barcode made up of black modules arranged on a white background, forming a square that is instantly recognizable. Unlike the traditional barcode, which can only be read horizontally, the QR code works in both dimensions (horizontally and vertically), allowing it to contain a much larger volume of information.

Designed to be scanned quickly using a camera (mainly those on smartphones), it provides instant access to a variety of digital content: web links, texts, contact information, videos, files, or even direct actions such as calling a number or connecting to a Wi-Fi network.

Example of a modern QR code.

How does a QR code work?

A QR code is not just a mysterious image. It is a structured system, designed to store and transmit information quickly, reliably and machine-readable. Visually, it appears as a square composed of modules (the small black and white squares) that form a coded pattern.

Each QR code contains several essential elements:

Position markers: These are the three large squares visible in the corners, which allow a device to identify the orientation of the code (regardless of whether it is tilted, upside down or twisted).

Data area: This is where the actual information is encoded. It can contain text, a link, a number, or even instructions such as “open an application” or “send an email”.

Error correction zone: This part allows the code to be read even if it is partially damaged, dirty or poorly printed.

Format and version: This data specifies the size and type of the QR code, so that the reading software knows how to interpret it.

Depending on the density of the content, a QR code may have more or fewer modules and take up more space on screen or on paper. For example, a link to a simple website will take up little space, while a long text or a complete digital business card will make the code more complex.

In summary, a QR code is a well-organized “visual container”, capable of transporting a variety of content in a reduced space, with great efficiency.

Where does the QR code come from?

The QR code was invented in 1994 in Japan by Masahiro Hara and his team at Denso Wave, a subsidiary of Toyota. Originally, this technology was developed to facilitate the traceability of automotive parts in production lines. Traditional barcodes were no longer sufficient to store all the information needed for industrial logistics.

The creation of the QR code thus responded to a simple problem: improving reading speed while increasing the amount of integrated information. The design of the code, particularly the black and white visual appearance, is inspired by the traditional Japanese game Go, known for its contrasting pieces and geometric patterns.

Although Denso Wave retained the copyright, the company chose not to enforce its patents to allow free and worldwide adoption of the technology.

How to read a QR code?

Reading a QR code is now largely facilitated by mobile technology. Most modern smartphones are equipped with a QR reader built directly into the Camera app. Simply point the camera at the code: a notification automatically appears with the contained information.

In some cases, specific applications can be used, especially on older Android devices or tablets that do not have a built-in reader. On computers, it is possible to analyze a QR code using a webcam or by uploading the image to free decoding websites.

Security warning

Not all QR codes are necessarily safe. There are malicious codes that can redirect to fraudulent sites or trigger unwanted actions. It is advisable to:

scan only QR codes from reliable sources;

avoid those displayed in public spaces without context (e.g.: sticker on a wall);

use a secure application or browser capable of detecting suspicious links.

What is a QR code used for in everyday life?

The QR code has quickly become established in many areas:

Restaurants: display of dematerialized menus, online ordering, contactless payment.

Transportation: electronic tickets for trains, planes or events, identity verification, secure access.

Healthcare: use in medical certificates, such as the health pass in France, but also to store vaccination or treatment data.

Commerce: access to product sheets, interactive advertisements, promotional coupons.

Education and culture: educational resources, guided tours, interactive supports in museums or exhibitions.

Technology and communication: quick Wi-Fi setup, sharing digital business cards, redirection to profiles on social networks or messaging services.

Example of using a QR code to access the menu in a restaurant.

What are the advantages and limitations of QR codes?

Advantages

High storage capacity: up to 7,089 digits or 4,296 alphanumeric characters.

Fast reading: hence the name “Quick Response”.

Damage tolerance: thanks to integrated error correction.

Content versatility: links, actions, data, files.

Ease of creation: many free generators exist online.

Low distribution cost: printable on all types of media.

Limitations

Not readable without a device: a smartphone or camera is essential.

No visibility on content: impossible to know what a code contains without scanning it.

Risk of phishing or malicious redirects: some QR codes can trap users.

Static code difficult to modify: once printed, a static QR code cannot be edited. On the other hand, dynamic QR codes allow information to be modified remotely, making them much more flexible in a professional or marketing context.

What is the future of QR codes?

The QR code continues to evolve. Dynamic versions now make it possible to analyze scan statistics, modify redirects or adapt content according to geolocation or the user’s language. Custom designs are also emerging, incorporating logos, colors or original shapes, without harming readability.

The future of the QR code therefore seems assured, particularly in an increasingly connected world where speed and simplicity have become common requirements.

Sources

https://www.iso.org/standard/83389.html

https://www.denso-wave.com/en/technology/vol1.html

https://www.gs1.org/standards/barcodes/2d

https://arxiv.org/abs/2404.05073