A USB OTG cable (Universal Serial Bus On The Go) is a cable that is specifically designed to work with portable devices with a USB port that can be switched to Host mode. In normal usage, when you connect your Nokia IT to a PC, the Noka IT is acting like a peripheral for the PC. In Host mode, this scenario is reversed, and the Nokia IT can be used as if it were a PC... allowing you to connect peripherals directly to your device.

A really good description can be found here:

http://www.internettablettalk.com/wi..._using_OS_2008