iRing app uses the front-facing camera on your device and advanced volumetric positioning algorithms to recognize and determine the exact position of the ring in relation to the selected device camera. This precise reading of the position of the ring is converted by the app into music or MIDI control messages. So in essence, iRing and the iRing companion apps track your movements and convert them into useful info your apps use to change things.
Because movements can be recognized along the three axis, with two rings you can control up to six parameters simultaneoulsy. On top of movements also certain gestures are recognized (like the rotation of the ring) greatly enlarging your music expression possibilities.