USB OTG (On-The-Go) allows users to connect removable storage devices like Pendrive on their mobiles or tablets. With OTG you can transfer any files from pendrive to mobile or mobile to pendrive. Some tablets also offers mouse and keyboard connect to transform it as mini pc. Latest mobiles are coming with big battery so this type of devices can act as power bank (i.e it can able to charge other mobiles or tablets) via OTG cable. If the device is compatible with Revese Charging then you can charge other devices. As the technology grows built-in OTG pendrives are releasing more in numbers.