Mirror Material
The mirror material is most often applied to a plane. It will allow you to simulate a mirror or a pane of glass in which the other surfaces in the scene will be reflected.
You can filter the surfaces that will be reflected using the Tag for Reflected Surfaces option. This option uses the tags assigned to surfaces in Shaper to limit the surfaces that are reflected. In a complex scene, this can significantly improve rendering time.
For more information on tags, see Tag Manager.