THE rectangles of a two-dimensional (2D) barcode are Mondrian-esque. The black-and-white codes represent data in grid form, which only a computer can decipher. They represent a hyperlink or piece of text, which can be read by scanning the code—for example with a mobile phone. No internet connection is needed. These encodings, often seen in the Quick Response (QR) format, are widely used in Japan and China, where (by one estimate) they enabled $1.65trn of mobile payments in 2016. But they are less familiar in North America and Europe, despite their appearance on airline boarding passes and shipping labels, and in apps used by the likes of Starbucks and Walmart. A Tumblr site founded in 2012 called “Pictures of People Scanning QR codes” has no entries—an intentional gag. Why are 2D codes employed so widely in some places and not in others?

Scannable codes became popular in Japan in 2002, when mobile internet access was still poor. Advertisers, publishers and handset-makers teamed up to popularise QR codes as a way to share information with customers. Japan led the field until recently, when the use of 2D codes in China boomed. Two Chinese digital-payment platforms, Tencent’s WeChat Pay and Alibaba’s Alipay, allow people to make contactless payments by scanning codes. A customer can either scan a merchant’s QR code, or the merchant can scan the customer’s account code. This allows mobile phones without near-field communication, which is built into modern Apple and Android phones, to make contactless payments. While Apple Pay and Android Pay are flourishing in America and Europe, the technology needed to support them is too expensive for many shops in poorer countries.

The QR code could soon flourish beyond East Asia, though. Apple has responded to the codes’ popularity in China by updating the camera app in iOS 11, the latest version of its mobile operating system. It now automatically recognises a QR code that encodes web links, map locations, contact cards and other data. Apple was not even the first to jump on the Asian trend. Other handset-makers (notably Motorola) have included QR-code recognition in their cameras, and some apps include code recognition in their camera features. These include WhatsApp, which allows users to confirm a contact’s identity with a QR code; the new generation of bike-sharing systems, which lack central docking stations and get riders to scan QR codes to unlock bikes; and SnapChat’s own version of 2D codes, which it launched in 2015. But Apple’s free upgrade means that QR-scanning will reach hundreds of millions of users worldwide.

Interest in QR codes has grown more rapidly following Apple’s launch. Shopify, an e-commerce software company, has created a tool to generate QR codes that customers can place on products, advertising and in stores. Apps and websites that allow designers to generate codes easily have gained new users. But the codes’ spread need not be limited to tech companies and advertising firms. Business cards, flyers, posters—all can benefit. For a real breakthrough, though, television advertisers and high-circulation periodicals would have to take QR codes more seriously. Then it might be time to update that Tumblr site.