QR Code

What is a QR Code?

code definition and meaning

While they may look simple, QR codes are capable of storing many data. However, no matter how much they contain, when scanned, the QR code should allow the user to access information instantly – hence why it is called a Quick Response code.

What are QR codes?

A QR code is a type of barcode that can be read easily by a digital device and which stores information as a series of pixels in a square-shaped grid. QR codes are frequently used to track information about products in a supply chain and – because many smartphones have built-in QR readers – they are often used in marketing and advertising campaigns. More recently, they have played a key role in helping to trace coronavirus exposure and slow the spread of the virus.

Standard barcodes can only be read in one direction – top to bottom. That means they can only store a small amount of information, usually in an alphanumeric format. However, a QR code is read in two directions – top to bottom and right to left. This allows it to house significantly more data.

The development team behind the QR code wanted to make the code easy to scan so that operatives did not waste time getting it at the right angle. They also wanted it to have a distinctive design to make it easy to identify. This led them to choose the iconic square shape that is still used today.

Are QR codes safe?

Attackers can embed malicious URLs containing custom malware into a QR code, which could then filtrate data from a mobile device when scanned. It is also possible to embed a malicious URL into a QR code that directs to a phishing site, where unsuspecting users could disclose personal or financial information.

Because humans cannot read QR codes, it is easy for attackers to alter a QR code to point to an alternative resource without being detected. While many people are aware that QR codes can open a URL, they can be less aware of the other actions that QR codes can initiate on a user’s device. Aside from opening a website, these actions can include adding contacts or composing emails. This element of surprise can make QR code security threats especially problematic.

How do QR codes work?

The patterns within QR codes represent binary codes that can be interpreted to reveal the code's data. A QR reader can identify a standard QR code based on the three large squares outside the QR code. Once it has identified these three shapes, it knows that everything contained inside the square is a QR code.

The QR reader then analyzes the QR code by breaking the whole thing down to a grid. It looks at the individual grid squares and assigns each one a value based on whether it is black or white. It then groups grid squares to create larger patterns

What are the parts of a QR code?

Quiet Zone - This is the empty white border around the outside of a QR code. Without this border, a QR reader will not be able to determine what is and is not contained within the QR code (due to interference from outside elements).

Finder pattern - QR codes usually contain three black squares in the bottom left, top left, and top right corners. These squares tell a QR reader that it is looking at a QR code and where the outside boundaries of the code lie.

Alignment pattern - This is another smaller square contained somewhere near the bottom right corner. It ensures that the QR code can be read, even if it is skewed or at an angle.

Timing pattern - This is an L-shaped line that runs between the three squares in the finder pattern. The timing pattern helps the reader identify individual squares within the whole code and makes it possible for a damaged QR code to be read

Version information - This is a small field of information contained near the top–right finder pattern cell. This identifies which version of the QR code is being read (see “Types of QR code” below).

Data cells - The rest of the QR code communicates the actual information, i.e., the URL, phone number, or message it contains.

What are the different styles of QR code?

It is possible to create QR codes in many different shapes and styles, but five types are most commonly found. They all do the same job – they just look slightly different.

QR code - This is the original version of the QR code created by Denso Wave in the 1990s. It's easy to identify by its three finder patterns in the bottom–left, top–left, and top–right corners.

Aztec code - While it looks similar to a QR code, the Aztec code, developed by Welch Allyn, contains only one finder pattern, right in the middle.

Maxi code - This type of QR code is used by the United States postal service. It's similar to the Aztec code in that it places the finder pattern in the middle, but it uses a honeycomb pattern instead of squares.

PDF417 - Invented in 1991 by Ynjiun Wang of Symbol Technologies, the oddly named PDF417 predates the QR code by three years. It looks like a mix between a QR code and a barcode and is easily recognizable by its rectangular shape.

Semacode - Developed by a software company of the same name, the Semacode is a data matrix that looks a lot like an ordinary QR code but doesn’t have recognizable finder patterns.

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