While not everyone uses AirPlay Mirroring to display their iPhone, iPad or iPod touch screen on a TV through an Apple TV, that capability is surprisingly popular with those who need to teach or demonstrate iOS apps.
In the iOS 6 days, you could get to AirPlay Mirroring by double-tapping the Home button, then swiping right as far as you could go, into the Music player controls where you'd see the AirPlay icon. With a tap on that icon, you could turn on mirroring. We've had pings from more than just a few readers who wonder where that capability has gone in iOS 7, so here's the simple solution: it's part of Control