Diffuse reflection is the reflection oflight from a surface such that an incident ray is reflected at manyangles rather than at just one angle as in the case of specular reflection. An illuminated ideal diffuse reflecting surface will have equal luminancefrom all directions which lie in the half-space adjacent to the surface (Lambertian reflectance).
A surface built from a non-absorbing powder such as plaster, or from fibers such as paper, or from apolycrystalline material such as whitemarble, reflects light diffusely with great efficiency. Many common materials exhibit a mixture of specular and diffuse reflection.
The visibility of objects, excluding light-emitting ones, is primarily caused by diffuse reflection of light: it is diffusely-scattered light that forms the image of the object in the observer's eye.