As we have been predicting, QR codes are arriving at some sort of critical mass in the US, and suddenly, you see them everywhere. Home depot has them on store displays. They’re on the news. A headstone maker is putting them on gravestones.

They may look like a maze puzzle to you, but to a smart phone with a (free) QR-reader app, they are a link to information, like a bar code on steroids.

Most current applications simply use the code to link to a website. At Home Depot, a QR code attached to a display model links you to the Home Depot web page about the product. The gravestone-maker similarly uses the QR code to link to a web page about the deceased. (The code, etched in stone, will probably outlast the web page.)

It is possible to pack plain text directly into a QR code, too. For example, the really dense QR code depicted here contains the first two paragraphs of this post.

What is it worth to building products manufacturers? For starters, you could link all your product data and online instruction videos to a QR code right on your product packaging. A contractor shopping at the distributor’s warehouse could find out everything he needs from the most accurate source: you. On the jobsite, he could access instant video instruction for workers. You could link him to customer service and technical support just as easily.

You can put a QR on your business card, too, for direct link to your website.

For the time being, while QR codes are still a novelty, they offer tempting guerrilla marketing opportunities. People will be curious and scan them just to find out what they link to. Print them on cards and leave a few at big job sites, on Home Depot shelves, at union halls. You can print them on stickers and find interesting places to attach them: a hard hat, a tool box, a product package.

They won’t be novel for long, though. Acceptance is moving rapidly.