The Lighting Shader plug-in performs per-pixel lighting, as opposed to default per-vertex lighting in Viz.
Note: This plug-in is located in: Plugins -> Shader -> Material
Specular Type: Shows the color that appears when light comes from a particular direction and bounces back from the surface in a mirrored direction. The specular color is the direct reflection of a directional light source. This is the typical effect of shiny metal and plastic. Specular color can be understood as a kind of shininess of color.