the screen like a television or computer screen, on which the reflected images of the radar are seen. It works by sending outsuper-high frequency radio waves which then bounce off objects, such as other ships or land masses, etc., within the range of the radar. These reflections are then reproduced as tiny electronic images. In this way other ships and objects can be observed and avoided. It is also used for navigation. The term is derived from radio direction and range. —AcademyLevel II Glossary