What a QR code is, and its history

What is a QR code?

A QR code (short for Quick Response) is a two-dimensional barcode: instead of lines read from left to right, it stores information in a grid of small black and white squares called modules, which are read across and down at the same time.

That's why a tiny space holds far more information than a traditional barcode: a web address, a contact card, Wi-Fi details or a piece of text. And any phone camera can read it from almost any angle.

Who invented the QR code?

The QR code was born in 1994 at Denso Wave, a Toyota group company. Its creator, engineer Masahiro Hara, was looking for a faster way to identify car parts in factories: barcodes at the time fell short, several had to be scanned per part and they were hard to read when dirty.

Inspiration came, as Hara himself has explained, from playing Go, the board game of black and white stones on a grid. That's where the idea of storing data in a grid came from. The challenge was for scanners to find the code instantly whatever its orientation: the answer was the three squares in the corners, with a ratio of black to white that almost never appears in printed text or images.

A free standard

Denso Wave patented it but chose not to charge for its use. That decision was key: anyone could create and read QR codes without paying licences. In 2000 it became an international standard (ISO/IEC 18004) and spread around the world.

“QR Code” is a registered trademark of DENSO WAVE INCORPORATED.

From the factory to your pocket

• 1990s: logistics and manufacturing in Japan.
• Early 2000s: the first camera phones in Japan ship with QR readers and the code jumps to advertising, magazines and tickets.
• 2010–2016: it reaches the rest of the world, but you need an app to read it, so adoption is slow.
• 2017–2018: the iPhone camera (iOS 11) and most Android cameras start reading QR codes without apps. The big leap.
• 2020: the pandemic turns the QR code into the way to see restaurant menus, pay contactless or show certificates.
• Today: it's on packaging, posters, tickets, invoices, payments, business cards and even headstones.

Types of QR codes

• Static QR code: the information is inside the pattern itself. To change it, you must generate (and print) a new code.
• Dynamic QR code: the code stores a short link that redirects to the final destination. You can change the destination anytime without touching the printed code, and see how often it's scanned. That's what QR Boost does.
• Micro QR and iQR: smaller or rectangular variants for industrial use.

What can a QR code store?

A QR code can hold up to 7,089 digits, 4,296 alphanumeric characters or 2,953 bytes. In practice, it usually stores:

• A web address (the most common).
• A contact card (vCard).
• Wi-Fi details to connect without typing the password.
• A ready-made email, text message or call.
• A location on the map.
• Payment or bank transfer details.

The more information it stores, the denser the pattern and the harder it is to read from a distance. That's why dynamic QR codes, which only store a short link, scan better. To see how it's read inside, check how QR codes work.

Good practice

• Print it with good contrast: dark code on a light background.
• Leave a clear margin around it (the standard asks for 4 modules).
• Size it right: at least 2 × 2 cm, plus 1 cm for every 10 cm of scanning distance.
• Add a call to action (“Scan me to see the menu”) so people know what they'll get.
• Test it with several phones before printing a thousand copies.
• Use a dynamic QR code if there's any chance the destination will change.