Hi Avi, I had the same question as you, it seemed contradictory with the information given and the examples like a chrome ball, that an incredibly smooth surface like say a perfectly smooth white marble will still have diffuse reflection as well as specular, I read this article on Wikipedia https://en.wikipedia.org/wiki/Diffuse_reflection#:~:text=A%20flat%20surface%20is%20indeed,continues%20to%20be%20diffusely%20reflected. that made it a bit clearer, apparently diffuse reflection happens just below the surface of an object, the light penetrates the object, and sort of bounces around inside and goes everywhere, there are very few materials that don’t allow this to happen, one being chrome, specular reflection on the other hand, happens above the surface, so let’s take the chrome ball as an example, chrome and other metals do not allow light to bounce below their surfaces, so no diffuse lighting, but because specular reflection happens on the surface, it has specular reflection, hope that made sense TLDR: According to physics, materials that can be penetrated below the surface by light will have diffused reflection, if the surface of that material happens to be smooth, it will also have specular reflection because that happens on the surface, not below it.