"So, what are QR Codes, you ask? Well, you know what barcodes are, like when you buy something at the store and the clerk scans a code to enter the item and amount into the till? The QR (Quick Response) Code is kind of like that, except that it offers much more information. Quite often the QR Code will give you a link to a website, or a text message, image, etc. To read the QR Code, you need to install a QR Code Reader onto your device. There are many available for free. I like using i-nigma, seen below. Simply open the app, point it at a QR Code and your device will do the rest. Try it with the code above. It should take you back to this blog."
Via John Evans, Alfredo Corell