With USB OTG you can control your device by connecting different peripheral devices like: - Mouse, Keyboard etc. with your smartphone or tablet . However, it should be noted that multiple button or function rich mice may not work. OTG also allows you to add various storage devices to your device , such as Hard-Disk, Pen-Drive, Card Reader, etc. Just so you can play Audio, Video from these external storage devices . Moreover, using the file manager on the device , you will not be able to transfer data from these storage devices.