QR Codes are two-dimensional barcodes. They have been around for a while, but it wasn’t until smartphones became the norm that they have really taken off as a marketing tool. QR Codes solve the problem of asking your audience to type long or complex URLs and web addresses into the tiny keypads on their phones – you can easily point them to the information you want them to see, when you want them to see it.
http://www.squarecode.biz/