Mosaics of black-and-white squares that look like tiny crossword puzzles are cropping up everywhere, from bus stop ads and cereal boxes to stickers on bananas, and they're changing the way people get information on the go.

These two-dimensional "matrix codes" are a way to encode information, such as the URL for a website or video, in a way that can be quickly scanned by a computer or mobile device. Use a smartphone or tablet to snap a photo of the matrix code on a real estate sign, for example, and it could provide basic information about the property or point you to a web page with all the latest listing details. No need to remember a complex URL or type it in manually — using your mobile device's camera, just point, shoot and surf.

The idea is that once you've caught someone's interest and they're paying attention to a sign or a piece of printed material, you can offer them a way to instantly get more information, sign up for e-coupons or enter a contest.

The codes come in various forms, most of them using black and white squares, but some using hexagons or multi-coloured triangles.

One of the most popular is the QR Code, distinguished by the large squares in three of the code box's corners.

QR stands for "quick response," and it didn't start out as a marketing tool. A Japanese subsidiary of Toyota, Denso Wave, originally created the QR Code as a way of tracking its inventory of automotive parts. You may have seen such codes on courier packages, or even on stickers on fruit, serving a similar purpose.

They were originally intended to be read using laser scanners, like bar code scanners at the supermarket but more reliable and much faster. Programmers soon found that cellphone cameras could also be used to read the codes, and their use quickly spread.

The codes are designed to hold a relatively large amount of data in a small space — just under three kilobytes of binary data, or more than 4,000 letters and numbers. The codes can be read at any angle and the data in them can be recovered even if part of the code is damaged or obscured.

Linking real world, internet

The most common use of matrix codes is to encode the address of a website so that cellphone users can quickly scan it and visit the site without typing in a complicated URL.

A QR Code used in this way becomes, in essence, a real-world hyperlink — a way to connect physical space to the virtual one. Tech giant Google has embraced the technology and Facebook has been experimenting with the codes as a way to link to user profiles.

The codes are especially popular in Japan where they've been used in advertising for years — in magazines, on posters and even billboards — so consumers can learn more about a product or enter a contest. The uptake of matrix codes in North America has been slower, but people are gradually catching on.

This QR code was created with the help of Google's API. It links back to this article. Google

A report from Mobio Technologies Inc., a Vancouver-based barcode techology company, says the use of its QR codes alone rose 9,840 per cent in the third quarter of 2011, compared to the same period in 2010. "We have not used any third party data. We do however believe this data is highly representative of the North American QR market as a whole," the report said. "QR barcode use continues to thrive as the newest and most interactive way to engage consumers. Consumers arenʼt passing up the opportunity to use their smartphones to scan QR barcodes to receive information, enter contests and even make purchases and donations."

A second-quarter 2011 report from 3GVision, which develops mobile barcode reading and image processing technology, says that Canada ranks fifth among Western countries in terms of the per-capita use of mobile barcodes.

The usefulness of the codes is growing as more and more people buy smartphones and tablets, and the potential uses are nearly endless:

• A movie poster might have a code that links to the movie's trailer.
• A magazine ad could link to a website where the reader can buy the product.
• Mail-order catalogues can use codes for individual items, so customers can quickly order them through their phones.
• Codes on takeout food and drink containers can contain or link to nutritional information.
• Tourism groups can label locations of interest within a community so that visitors can go on self-guided tours and call up historical information on ther phones.
• The University of Guelph in Ontario added QR codes to its admissions handbook sent to high schools.
• The National Post uses a different matrix code scheme — EZcode, created at a Swiss university — to link from its newspaper pages to its website.

More than links on paper

The codes don't just show up on paper, but on screens, too. Websites and blogs that discuss apps for smartphones will sometimes include a matrix code link to the app, providing an easy way to download it directly to your phone.

And TV shows have used the codes for the same purpose. The Weather Channel in the U.S. puts a QR Code on-screen so people with Android phones can download its weather app.

The use of matrix codes can go well beyond linking to a website, though. Some tech-savvy business people put matrix codes on their business cards that contain all their contact information in the vCard file format. Scanning it adds the person's contact information to a smartphone or tablet's address book.

A Coca-Cola promotion in Japan for a new iced tea offered two free bottles to people who scanned a QR Code on a poster. They would then take the code from the poster to a vending machine that accepts payment via cellphone to get the free sample.

This summer, British beach volleyball duo Zara Dampney, 24, and Shauna Mullin, 26, rented their rears to an advertiser, allowing their sponsor to print on the back of their bikini bottoms. When fans snapped a photo of the QR code printed on the stars' behinds, they were taken to the sponsor's website and offered a deal.

Vancouver's Mobio Identity Systems created a mobile payment app for the iPhone that uses QR Codes and links to a user's credit card. Mobio codes have appeared in Joannie Rochette's iheartmom video campaign for the University of Ottawa's Heart Institute. They have also been put on the seats at EverBank Field, home of the NFL's Jacksonville Jaguars — fans can order food to be delivered right to their seats by scanning the code.

The European Union has passed a bill cracking down on counterfeit medicine that would label genuine drugs with matrix codes that could be scanned in pharmacies.

And a gravestone company in Japan is building tombs with QR codes that can be scanned by a cellphone or other devices to get more information on the deceased, including pictures and video.