Some surfaces are shinier than others (for example a wet fish has a shinier surface than a dry leaf). By mapping a texture to the Specular attribute of an object’s material, you create a specular map which lets you describe how shine appears on objects (by controlling highlight).Shiny objects reflect light directly; matte objects diffuse light. Specular highlights show the places on the object where the light sources are reflected at consistent angles; reflections on an object show, among other things, light bounced from surrounding objects.
Specular highlights depend directly on the view (camera), not the position of the light, like diffuse shading does.
The size of a specular highlight on a surface makes the surface look either flat or shiny.
Note: Only materials with specular attributes (Anisotropic, Blinn, Phong, and PhongE) have surface highlights. The specular highlight is the white shiny glow on the material.