RADAR was coined in 1940 by the United States Navy as an acronym for Radio Detection and Ranging or Radio Direction and Ranging. Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formation and terrain. Radar was developed secretly for military use by several nations in the period before and during World War II (1 September 1939 – 2 September 1945).
Air traffic control: The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots.
Radar astronomy: Radar Astronomy is a technique of observing nearby astronomical objects by reflecting microwaves off target objects and analyzing the reflections.
Air defence system: Radar is used to establishing communication platform and can include ground-and air-based weapon systems, associated sensor systems, command and control arrangements.
Antimissile systems: A point-defense weapon system for detecting and destroying short-range incoming missiles and enemy aircraft which have penetrated the outer defenses.
Marine radars: To locate landmarks and other ships.
Similarly a radar is also used in aircraft anti-collision systems, ocean surveillance system, whether monitoring system.