What does Identify Friend or Foe system do?

Answer 1

Identify Friend or Foe system, IFF for short, does exactly what it implies: It lets aircraft and aircraft tracking systems know if an aircraft is an enemy or a friend. Almost every single plane in the sky has a radio transponder that sends data out to any other aircraft in order to identify itself. In the commercial/civilian world, this is also one way that Air Traffic Controllers can keep track of aircraft on their radar screens. IFF is also used in fighter planes as well as by Surface to Air Missile systems to ensure only enemy airplanes are targeted and shot at.