Raytracing is a type of rendering where the path of individual light rays are calculated between the camera and the light source. To find out more about how to raytrace to produce shadows, see Raytraced shadows in the Lighting guide.
To find out more about how to raytrace to produce reflections, see True reflections in the Shading guide.
To set raytracing quality, adjust the settings in the Raytracing Quality section of the Render Settings window.