QR Codes: How they work and how to stay safe

Discover everything about QR codes: How they work, safe creation practices, and their versatile applications in daily life and business.


QR code definition and meaning

“QR Code” stands for “Quick Response Code”. 

It’s a type of barcode designed for rapid readability and high storage capacity. Originating in the automotive industry, QR codes have evolved into a widely used tool in various sectors. Their unique pattern of black squares arranged on a white background encodes information that, when scanned, provides instant access to data, websites, or other digital resources. This immediate data query is the reason for the name Quick Response Code, which enables fast and efficient interaction.

What are QR codes?

QR codes, easily recognized as those square-shaped barcodes, are designed to store information in a way that digital devices can quickly read. These codes, made up of black and white squares, are common in various settings, notably for keeping tabs on products as they move through a supply chain. Moreover, with most mobile devices having the capability to scan QR codes, these codes have become a staple in marketing efforts. Notably, in recent times, they’ve been instrumental in tracking and slowing the spread of the coronavirus by tracing contacts.

This innovative QR code technology was pioneered in 1994 by Denso Wave, a branch of Toyota. Their goal was simple yet ambitious: to track vehicles and parts more accurately during the manufacturing process. To do this, they created a barcode that could store more than just numbers and letters—it could also include Japanese kanji and kana characters.

What sets QR codes apart from the standard barcode is their ability to store more information. Traditional barcodes are like one-dimensional images, read from top to bottom, and can only hold a limited amount of data. QR codes, however, can be read both vertically and horizontally, giving them a two-dimensional structure. This means they can hold a lot more information, making them a more versatile choice for various applications.

QR codes are versatile, capable of holding various types of data, including website links, phone numbers, or text up to 4,000 characters.

Their utility extends into numerous practical applications. For instance:

  1. App Downloads: They can serve as direct links to apps in the Apple App Store or Google Play, streamlining the download process.
  2. Account Security: QR codes enhance online security by authenticating user accounts and validating login credentials swiftly.
  3. Wi-Fi Connectivity: These codes can contain Wi-Fi network details, such as the network name SSID, password, and encryption type, simplifying the connection process.
  4. Payments: They facilitate smooth financial transactions by encoding and transferring payment details.
  5. Innovative Uses: The versatility of QR codes is exemplified by unique applications, such as a UK-based company, QR Memories, which embeds them on gravestones. This allows visitors to scan and access an online tribute or obituary, creating a digital memorial for the departed.

The scope of QR codes goes beyond these common uses, marking their presence in various aspects of daily life and offering a seamless blend of the physical and digital realms.

Best practice: How to scan QR codes

Most modern smartphones come equipped with QR scanners, often integrated into the camera application, making scanning QR codes a breeze. These scanners are essentially tools designed to decode the information embedded in QR codes.

Tablets, like the Apple iPad, are also equipped with cameras that have built-in QR reading capabilities, ensuring convenience across various device types.

For some older devices, a specific app may be necessary to read QR codes. These apps are easily accessible and can be downloaded from the Apple App Store or Google Play.

The process of scanning a QR code with your device is simple and user-friendly:

  1. Open the Scanner: Launch the QR reader app or your device’s camera.
  2. Point and Scan: Direct your device’s camera at the QR code. The great thing about QR codes is their user-friendly design—you don’t have to align your camera perfectly; it can capture the code from various angles.
  3. Instant Results: Once the code is scanned, the encoded data appears immediately. For example, if the QR code contains a contact card, your device will promptly offer to save this contact information.

This streamlined method allows for the instant digital retrieval of information, making QR codes a practical and efficient tool in everyday life.

While QR codes are generally safe, they can be manipulated by scammers because they all appear similar. A malicious QR code may lead you to a spoofed website designed to drop different malware types or steal your sensitive data, like your login credentials, credit card information, or money. In one incident, cybercriminals were using fake parking meter QR codes to steal money through phishing websites.

Does a QR code collect my personal information?

Software used to generate QR codes typically does not gather any personally identifiable information. However, it does collect certain types of non-personal data, which can be accessed by the creators of the QR code. This includes:

  • Location Data: Identifying the geographical location where the QR code was scanned.
  • Scan Metrics: Recording the number of times the QR code was scanned and the specific times of each scan.
  • Device Information: Determining the operating system of the device used for scanning, such as whether it’s an iPhone or an Android device.

This information, while not personally identifying, offers valuable insights into the usage patterns and reach of the QR code, assisting creators in understanding and optimizing the effectiveness of their QR codes.

Can someone hack a QR Code?

Yes, QR codes can be compromised. Hackers may manipulate QR codes to conduct malicious activities in two primary ways:

  1. Malicious URL Embedding: By encoding a harmful URL into a QR code, attackers can lead individuals to download malware or unwanted software. Once scanned, these QR codes can initiate the download and installation of malware, putting personal data at risk.
  2. Phishing Expeditions: Similar to malicious URL embedding, hackers can also direct users to phishing websites through a QR code. These websites, often masquerading as legitimate sites, aim to trick individuals into entering sensitive information, such as login credentials or financial data, thereby compromising their security.

Protective Measures:

  • Verify Before Scanning: Always confirm the source of a QR code before scanning. If it’s from an unknown or suspicious source, avoid scanning it.
  • Use Secure QR Code Scanners: Some QR code scanner apps offer additional security features, like checking the URL for known security threats before opening it.
  • Stay Informed: Regularly update yourself on the latest cybersecurity practices and educate others about the risks associated with QR codes.

By understanding these risks and taking the necessary precautions, users can significantly mitigate the potential threats posed by compromised QR codes.

Checklist: How to create QR codes safely

Creating QR codes is a convenient method to swiftly share information. However, it’s essential to ensure that the creation process is secure to safeguard your data and the integrity of the QR code. Follow this best practice checklist to create QR codes safely, while avoiding bullet points for a cleaner presentation.

  1. Select a reputable QR code generator: Choose well-known and trustworthy QR code generators. Steer clear of tools or apps that appear dubious or have negative reviews. Opt for a generator that provides advanced security features.
  2. Double-check your content before encoding: Carefully verify every detail of the information you’re embedding into the QR code. Confirm every character of a WiFi password to prevent unauthorized access. For URL redirections, ensure the link is accurate and directs users to the correct website.
  3. Customize your QR code (optional): Take advantage of customization options such as color, frame, and shape to personalize your QR code. Make sure these customizations do not hinder the QR code’s readability or functionality.
  4. Encrypt and add password protection (for sensitive information): Encrypt the data within the QR code to shield it from unauthorized viewing. For an extra layer of security, especially with sensitive content, add password protection to the QR code.
  5. Create and test the QR code before distribution: Generate the QR code using your selected generator. Test the QR code across different devices and scanning applications to ensure its proper functionality. Verify that the QR code accurately points to the intended information or destination.
  6. Monitor your QR code: Regularly check the destination of the QR code, particularly if it redirects to a website, to confirm that it hasn’t been tampered with or compromised. Monitor the scan statistics and traffic to detect any unusual activities or potential security issues.
  7. By following these steps, you can create QR codes that are not just effective in conveying information but are also secure, ensuring a trustworthy experience for both the creator and the end-users.

How do QR Codes work?

QR codes function by encoding data into a compact, square pattern of black and white squares. These patterns are read by a QR scanner or a smartphone camera. The scanner interprets the unique arrangement of squares, translating it into digital information such as text, website URLs, or other data types. The efficiency of QR codes lies in their ability to store a large amount of data in a small space and to be easily scanned, making them a versatile tool for quick data retrieval and seamless user interaction.

What are the parts of a QR Code?

A QR code is meticulously structured, comprising several components that facilitate accurate data encoding and decoding:

  1. Data Modules: These are the black and white squares that represent binary information, with black squares indicating ‘1’ and white squares ‘0’. This binary sequence encodes diverse data types such as numbers, letters, or URLs.
  2. Position Markers: Located in three corners of the QR code, these distinct square patterns enable scanners to identify the orientation of the QR code, ensuring the data is interpreted correctly regardless of how the code is angled.
  3. Quiet Zone: A mandatory clear area that borders the QR code. This space separates the code from other graphical elements, preventing misreads.
  4. Alignment and Timing Patterns: These patterns, appearing as smaller squares within the larger grid, help maintain the QR code’s structure and ensure its readability, especially important when the code is distorted or partially obscured.
  5. Version Information: QR codes come in various sizes, known as versions, ranging from Version 1 (21×21 modules) to Version 40 (177×177 modules). The version information, encoded within the QR code, indicates its size and, consequently, its capacity to store data.
  6. Data Cells: These are individual units within the data modules, each holding a bit of information. The arrangement and number of these cells determine the volume and type of data the QR code can carry.

Understanding these components is essential for recognizing how QR codes efficiently store and transmit information, ensuring data integrity and accessibility.

Different types of QR Codes 

QR codes are highly versatile and can serve various purposes, largely due to their ability to operate in different “input modes.” These modes dictate the type of data that can be stored in the QR code, as indicated by the “version information field” within the QR code itself. The four primary versions, or input modes, are as follows:

  1. Numeric Mode:
    1. Specially designed for numbers 0-9.
    1. Offers the most efficient data storage, allowing for up to 7,089 characters.
  2. Alphanumeric Mode:
    1. Accommodates numbers 0-9, uppercase letters A-Z, and a select group of symbols ($, %, *, +, –, ., /, and :), including space.
    1. Can store up to 4,296 characters.
  3. Byte Mode (Binary Mode):
    1. Supports characters from the ISO-8859-1 character set (essentially, the Latin alphabet).
    1. Has a capacity of 2,953 characters.
  4. Kanji Mode:
    1. Originally designed for double-byte characters from the Shift JIS character set, primarily for encoding Japanese characters.
    1. The least space-efficient, allowing for 1,817 characters.
    1. An Extended Channel Interpretation (ECI) mode is available for the kanji character set UTF-8, though it’s worth noting that some newer QR readers might not support this character set.

In addition to these primary modes, there are two specialized modes that modify or extend the functionality of QR codes:

  • Structured Append Mode:
    • Enables the encoding of data across multiple QR codes.
    • Up to 16 QR codes can be interconnected and read in sequence.
  • FNC1 Mode:
    • Allows a QR code to function akin to a GS1 barcode, which is widely used in supply chain management.

It’s important to note that a single QR code can incorporate multiple modes, provided that the correct version information is embedded within the code, ensuring accurate interpretation and decoding of the stored data.

Styles of QR codes 

Various shapes and styles of QR codes are available, but five types are particularly prevalent. While they all serve the same fundamental purpose of storing and presenting data, they differ in appearance and structural design.

QR Code:

  • The classic and most recognized version, originally developed by Denso Wave in the 1990s.
  • Characterized by its three distinctive finder patterns located in the bottom-left, top-left, and top-right corners, which help scanners identify and read the code correctly.

Aztec Code:

  • Though it bears resemblance to a QR code, the Aztec code, created by Welch Allyn, stands out with its unique single finder pattern positioned centrally.
  • This central finder pattern aids in the code’s orientation and readability.


  • Employed primarily by the United States Postal Service.
  • Similar to the Aztec code in having a central finder pattern, but distinct with its honeycomb pattern rather than squares, lending it a unique appearance.


  • A precursor to the QR code, the PDF417 was invented in 1991 by Ynjiun Wang from Symbol Technologies.
  • It presents a blend of QR code and traditional barcode aesthetics, easily identifiable by its elongated, rectangular shape.


  • Crafted by a software company bearing the same name.
  • Resembles a standard QR code but lacks the distinct finder patterns typically associated with traditional QR codes, offering a more streamlined appearance.

Each of these code types, with their distinct structures and designs, caters to specific scanning needs and applications, demonstrating the versatility and adaptability of this data storage technology.

Static vs. Dynamic QR codes 

Static QR codes can’t be modified after creation because the data in a static QR code is ingrained. They’re most suitable for fixed data such as network passwords or serial numbers. By contrast, Dynamic QR codes are more flexible because they direct users to a URL, which can be modified.

QR codes: real world examples 

Having explored the different types of QR codes and their unique capacities for data storage, let’s transition to seeing these codes in action. The practical applications of QR codes are as varied as their types, weaving into the fabric of daily life and industry in innovative ways. Now, let’s take a closer look at how these varied types of QR codes manifest in real-world scenarios, demonstrating their versatility and impact.

In Event Ticketing: QR codes have revolutionized event entry, replacing traditional tickets. Attendees can now carry their tickets on their mobile devices, where a simple scan at the entrance ensures swift and secure admission.

In Interactive Advertising: Beyond mere redirection to websites, QR codes in advertisements now offer immersive experiences. Scanning a code might lead to an interactive video, a virtual tour, or exclusive content, significantly enhancing engagement.

In Personal Identification: In some regions, QR codes are part of digital ID systems. Scanning the code on a digital ID can quickly verify a person’s identity or share relevant information in a controlled manner, ensuring privacy and efficiency.

On product packaging: A glance at your favorite product’s packaging might reveal a QR code, serving as a portal to comprehensive product details, nutritional facts, or even exclusive offers, enhancing the shopping experience and offering added value to the consumer.

During the Covid-19 pandemic: The health crisis accelerated the adoption of QR codes, especially in contact tracing efforts. In many countries around the world, establishments such as bars and restaurants leveraged these codes for seamless check-ins via the NHS Covid-19 tracing app, playing a critical role in curbing the virus’s spread by notifying patrons of potential exposure.

In restaurant menus: To minimize physical contact, many restaurants have adopted QR codes for menu access. Patrons simply scan the code to view the menu on their smartphones, order, and even pay, ensuring a contactless and smooth dining experience.

In public transportation: QR codes are increasingly being used in public transport systems for ticketing and information. Commuters can scan a code to purchase tickets, access schedules, or get real-time updates, simplifying their travel experience.

In networking and business cards: Professionals are embedding QR codes in their business cards. A scan can reveal the individual’s portfolio, LinkedIn profile, or other professional platforms, making networking more dynamic and informative.

In these applications, QR codes have demonstrated their adaptability and utility, proving to be an invaluable tool in modernizing and simplifying interactions, transactions, and information dissemination across a multitude of sectors.

Related articles:

What is malware?

What is phishing?

What is a phishing email?

What is social engineering?

What is digital footprint?

What is a data breach?


How do I know if a QR code is safe?

Ensure the QR code originates from a trusted source. If you're unfamiliar with the company or linked sites, consider refraining from scanning. Furthermore, any misspellings or typos on the webpage housing the code could signal its lack of legitimacy. Stay cautious to protect your online safety.