What is USB On-The-Go (USB OTG)?

Introduction to USB On-The-Go

The USB On-The-Go (OTG) function allows a phone or tablet to use some USB devices like keyboards and flash drives directly. When a phone is connected to a computer wth USB OTG the computer appears to the phone as an external storage device. When you connect a phone or tablet to a computer with a normal USB cable the computer sees the phone as external storage like a flash drive or external hard drive.

Here is the usb.org official specification for USB On-The-Go.

What is needed to use USB On-The-Go?

Many smartphones and tablets now have USB OTG. Usually this is a USB-C port that specificly has OTG capability. The feature list of the phone should indicate if OTG is

supported. There are also apps like OTG Checker for Android to check for compatabilty. Additionally, USB OTG requries a USB OTG cable and will not work with a regular USB cable. USB OTG cables are available with USB-C, USB-A, Micro USB, and some have both USB-C and USB-A. You can think of the cable as being a USB hub where you would plug in external devices but attached to your phone.

Using USB On-The-Go

Plugging a USB OTG cable into a phone or tablet provides one or more USB ports that are slave to the phone. A keyboard plugged into a USB OTG port should immediately be live and available to the phone. Likewise with a flash drive or other external device. With the cvable plugged from the phone to a PC or laptop, the computer will show as external storage on the phone, the reverse of what happens with a normal USB cable.