A material is data that you assign to the surface or faces of an object so that it appears a certain way when rendered. Materials can affect object color, glossiness, opacity, and so on.
Color
The diffuse color is the color that an object reflects when illuminated by "good lighting," that is, by direct daylight or artificial light that makes the object easy to see.
Specular Color
Specular color is the color of highlights on a shiny surface. The highlights are reflections of the lights that illuminate the surface. For a naturalistic effect, set the specular color to the same color as the key light source, or make it a high-value, low-saturation version of the diffuse color. You can set the specular color to match the diffuse color. This gives a matte effect, making the material appear less shiny.
Shininess
The shininess of a material describes how smooth the surface is. We associate small strong highlight area with very shiny materials and large weak highlight areas (or no highlights at all) with dull materials. This control varies between 0 and 1 and defines the strength of the specular highlight region. A setting of 0 is a perfectly dull material and a setting of 1 is a very shiny material.
Transparency
Transparency or Opacity describes if something is visible (opaque), invisible (transparent), or partially visible.