Instrument Flight Rules (IFR) are regulations under which a pilot operates an aircraft in weather conditions that are not clear enough for visual navigation. IFR allows pilots to fly using instruments and navigation aids, ensuring safe travel even in low visibility situations, such as clouds or heavy rain. Under IFR, pilots must follow specific procedures and communicate with air traffic control to maintain safe distances from other aircraft. This system relies on instruments like altimeters and navigation systems, enabling pilots to navigate and control the aircraft effectively, regardless of external weather conditions.