QR (Quick response) code is a two-dimensional bar code. It is a black square pattern on a white background in which the text data are encoded.
It is usefull for transfering contact details or url's from computer screen straight into mobile phone with a camera and installed QR reader.
In order to scan the code with your phone's camera you have to install a QR code reader on your phone. You will need to install it just once.
Search the app store or market for QR code reader and install it. There are many available, most of them free.
Here are some most popular:
BeeTag
UpCode
mobiletag
QR code can basically contain any information. It can display plain text, contact details in a form of business card, location on a map or link to your website.
To create your own code is easy. Simply use Free QR code generator and have your code created within seconds.