"A QR Code is a matrix barcode (or two-dimensional code), readable by QR scanners, mobiles phones with camera, and smartphones. The code consists of black modules arranged in a square pattern on white background. The information encoded can be text, URL or other data.
Common in Japan, where it was created by Japanese corporation Denso-Wave in 1994, the QR code is one of the most popular types of two-dimensional barcodes. QR is the initialism of Quick Response, as the creator intended the code to allow its contents to be decoded at high speed. "(from Wikipedia)
Plus they look cool!
Generate yours here
Then download a QR reader from the itunes app store to read it.