What Is a QR Code? History, How It Works and Business Uses

A QR code is a square of black and white dots that stores a small piece of information, such as a link, a phone number or text, and a phone camera can read it in seconds. You see it on menus, signs, products and payment screens.

This guide explains what a QR code is, where it came from, how a phone reads it and how businesses use it, with practical points before printing. It is also one of the easiest ways to share a digital business card without anyone typing an address.

What is a QR code?

According to Wikipedia, it is a two-dimensional matrix barcode that stores data in a square grid of black and white modules. A traditional striped barcode stores a few digits in one direction; a QR code stores data in two, so it holds far more.

The history of the QR code

It was created in 1994 by Masahiro Hara at Denso Wave, then part of the Japanese company Denso, to track car parts in factories. As the official QR code site explains, old barcodes held only about 20 characters, so the team designed a code holding roughly 7,000 digits and reading more than ten times faster.

Importantly for users, Denso Wave kept its patent but declared it would not exercise it, and published the specification. Anyone can generate a QR code for free. "QR Code" itself is a registered trademark of the company.

How does a phone read a QR code?

1. The camera captures the image and finds the three large squares in the corners, which show position and orientation.
2. The phone splits the code into small modules and turns black and white into binary data.
3. It applies error correction to recover the data even if part is dirty or damaged.
4. It shows the content, usually a link the user opens with one tap.

QR uses Reed-Solomon error correction in four levels: L about 7%, M about 15%, Q about 25% and H about 30%. A higher level resists more damage but holds less data. The standard behind it is ISO/IEC 18004.

What can a QR code store?

A golden rule: the less you store, the clearer the code and the easier it scans. That is why the best code carries a short link that leads to a richer page.

QR code uses for business

• Restaurants and cafes: a digital menu on every table.
• Shops: a Google review or WhatsApp link at the counter and window.
• Business cards: a code on the back opening your details and a save-contact button.
• Packaging: instructions, warranty and order tracking.
• Trade shows: a sign that collects visitor details.
• Payments: a page that gathers transfer links.

Wikipedia notes that use grew during COVID-19 for touchless menus and contact tracing.

Static or dynamic QR code?

A static code holds the address inside the image, so it cannot change after printing. A dynamic one holds a short link you can redirect later, and it lets you count scans. Read more in dynamic QR code.

In Wslat every code points to a short link you can redirect at any time, so you never reprint if your page changes. The dashboard shows scans so you can measure each sign.

Tips before you print

• Leave a white margin of at least four modules around the code.
• Use strong contrast: a dark code on a light background.
• Do not shrink it too far; test from the real scanning distance.
• Test on more than one phone before printing the whole batch.
• Add a call to action such as "Scan to see the menu".

More details in QR code printing. If you wonder how it compares with tapping, see what is NFC. And if you want a code that opens a digital business card that is always up to date, that is exactly what Wslat provides.

QR code versions and size

Codes range from version 1 at 21 by 21 modules to version 40 at 177 by 177. The more data you store, the more modules there are, and the smaller and harder to read each one becomes at distance.

The practical result: choose a short link that gives a simple code with large dots. A simple code scans quickly even on rough paper or from a distance, and does not need very high print resolution.

Mistakes beginners make

• Encoding a very long link, which crowds the code.
• Putting a large logo over the code and exceeding its error correction.
• Using pale or inverted colours that some cameras cannot read.
• Printing a static code, then finding a typo in the link after distribution.
• Not tracking scans, so you never know which sign works.

Avoid these and your code will serve you for years without trouble.

FAQ

What does QR stand for?

Quick Response, named for how fast it can be read.

Is a QR code free?

Yes. Denso Wave decided not to exercise its patent, so codes can be made and used without a licence.

How do I scan a QR code?

Open your phone camera and point it at the code. A link or prompt appears for you to tap.

Does a QR code work if part of it is damaged?

Often yes, thanks to error correction that can recover up to about 30% at level H.

Does a QR code expire?

The code itself does not, but the link it points to can stop working. That is why a short link you control is better.