Reflection in Computer Graphics is used to emulate mirrors and shiny surfaces.
Mirror
Mirror reflection is accomplished in a Ray Trace renderer by following a ray from the eye to the mirror and then calculating where it bounces from, and continuing the process until no surface is found, or a non-reflective surface is found.
Specular
Specular reflection is the mirror-like reflection of light from a surface. Specular Reflection on a shiny surface like tile, or a wood floor can add to the Photorealistic effects of a 3D rendering.
The image on the right has specular reflection on the floor which emulates a shiny effect.