I get tons of people asking me about OTG. It stands for USB On The Go. Probably one of the most important features of an Android Tablet (besides the security and customization). It was developed in 2001 to facilitate communication between devices via USB (both peripherals and other devices) and push power and data over the same wire (simple as I can make it). Android developers frequently refer to it as USB Host mode:
I'll post a few more links if anyone is interested. There are different versions of OTG, not just one. Each manufacturer handles the spec very differently. It is absolutely necessary to understand this if you are creating a custom solution for deployment in a vertical use-case or in a heavily regulated industry.
For information on how devices handle OTG, use this app on the device. There are others however I've used this with some success:
One key thing with OTG is to test, test, test. Getting it right is an iterative process. Can't be done overnight and it is tricky as it is where hardware and software from multiple vendors usually meet up. But when it works, it is really cool. -Fin