USB OTG - USB On-The-Go
Short for USB On-The-Go, an extension of the USB 2.0 specification for connecting peripheral devices to each other. USB OTG products can communicate with each other without the need to be connected to a PC. For example, a digital camera can connect to a PDA, or a mobile phone can connect to a printer or a scanner, as long as all the devices are USB OTG-compatible. USB OTG grew from the increasing need for portable devices to be able to communicate with each other as the culture of technology moves away from a PC-centric world.
One of the important features of USB OTG is that the standard does not require a host PC in order for the devices to communicate. USB OTG devices, known as dual-role peripherals, can act as limited hosts or peripherals themselves depending on how the cables are connected to the devices, and they also can connect to a host PC.