Chances are, you've seen a QR code. These black and white patterns are appearing in newspaper and magazine ads, on flyers you receive in the mail, and even on billboards. They are used to encode some sort of information that you may want, whether it's in the form of a URL, an address, a phone number, or something else.
To read QR codes, you need a camera-equipped cell phone and a compatible QR code reader. Here are some of the best QR code readers available today.
BeeTagg Multicode Reader
A fast QR Code reader for the iPhone. It costs $1.99.
Qrafter provides a QR Code reader for the iPhone and other iOS devices, and an online QR Code generator. It's free, but ad-supported; you can pay 99 cents to have the ads removed.