A QR ("quick response") code is a square barcode that makes getting URLs, location coordinates, any text or contact information onto a phone fast. With a barcode scanner app installed, you just point your phone's camera at the code to read its contents. Here's what reading this QR code looks like on my Android phone, using an app simply called "Barcode Scanner."

To find a scanner application, Google "QR Reader" and the model of your phone. (If you've got a favorite scanner app that you're using, let us know in the comments.)

Encoding a regular URL is a fine use of QR codes—especially lengthy and complicated URLs on movie and event flyers—but one of my favorite uses of QR codes is swapping mobile app recommendations with your friends. Since you can't search the Android Market on the web or in desktop software, you're always stuck tapping in search terms by hand. The App Referer app generates QR codes for every one of your applications. So if you want to "give" that app to a friend, you call up the QR code, and your pal can scan your phone's screen.

You'll also see QR codes on web pages, in store windows, on business cards, and on conference badges. You can generate your own QR code with the information you want others to be able to read onto their phones quickly too. This QR code generator can embed a URL, text, a phone number, or an addressed and ready-to-send SMS message into a QR code.

If you Google "QR code generator" you'll find others, but beware of generators that force a redirect through their site when someone scans the resulting code and gets a URL. (For example, this generator has options to encode Google Maps coordinates, social network information, and Vcards and can print t-shirts and stickers from the codes it generates, but if you enter a simple web site URL it creates a redirect through the qrstuff.com site.)

Speaking of stickers, now I just need to print a few with my code to stick on my laptop, phone, and conference badges.

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