USB On-The-Go - definition
OTG (On-the-go) has been introduced back in 2001, so that devices with USB OTG support can have the compatibility to get connected to external peripherals such as mouse, keyboards, pen drive, memory chips and so on. Still now most of the phone manufacturers are providing OTG support to their device so that the data can be transferred more easily without having a bulk desktop/laptop or any computer system.