After many false starts, QR codes are finally taking off.
EREAL boxes are, by and large, poor works of literature. Yet many people sit at breakfast reading them over and over again.
Last year Kellogg's realised it could make its packets more entertaining-and guessed that people also had their phones to hand (anything beats talking to the family).
The cornflake-maker put 2D codes, better known as QR (for quick response) codes, on its Crunchy Nut boxes in America.
基于此，凯乐格在其在美国出售的Crunchy Nut麦片的包装盒上加上了二维码，或称QR码（QR即快速反应"Quick Response"之意）。
When scanned, these took cereal-munchers to a video of dawn in, say, Washington state.
The idea was to push cereal as an all-day snack: "It's morning somewhere."
QR codes-squares of black-and-white patterns-have much to recommend them.
They store far more information than plain, old bar codes.
For example, they can fit in web addresses and logos.
And they are cheap. They have been popular in Japan for years, but elsewhere have for a while been touted as the next big thing. (In 2009 this newspaper said they were "on the point of breaking out".)
Over the past year, QR codes have quietly slipped into the marketing mainstream.
Three-quarters of American online retailers surveyed by Forrester, a research firm, use them. In April nearly 20% of smartphone users in America scanned one, up from 14% in May last year (see chart 1).
According to comScore, another research company, more than two-thirds of Americans and Europeans who scan QR codes do so in order to obtain information about a product.
Japanese smartphone-owners, by contrast, are most likely to download a discount coupon or a special offer (see chart 2).
Scanlife, a provider of QR code services, saw the number of unique users scanning codes through its system triple in the year to March.
One reason for the rise is the proliferation of smartphones with high-quality cameras and the corresponding decline in data charges.
It also took time for people to realise why advertisements contained mutant crosswords.
And perhaps most important, marketers have only now worked out how best to use QR codes. Simply sending customers to the company website is not enough, says Melissa Parrish, an analyst at Forrester.
In-store promotions are catching on. Coupons are always popular. Real-world treasure hunts have also been successful.
For marketers, QR codes bridge the gap between offline and online worlds.
Customers who use them are, in effect, asking to be told more about the company. The success of a campaign is easy to measure by the number of scans.
Expect to see a lot more of those funny little black-and-white patches.