Coronagraphs are devices used in telescopes to block out bright light from a star or other celestial object in order to observe fainter objects nearby, such as exoplanets or debris disks. They work by creating an artificial eclipse, or coronal hole, in the telescope's field of view, allowing for the detection and study of objects that would otherwise be obscured by the glare of the star. Coronagraphs are an essential tool in the search for exoplanets and understanding the dynamics of planetary systems. They are also used in solar research to study the Sun's outer atmosphere, or corona.