What is diffuse light?

In fact, diffuse light refers to diffuse reflection of light. Contrary to specular reflection, when parallel light shines on an uneven reflecting surface, the light will reflect in all directions, and such reflected light is called diffused light.

Everything we can see in our life except light itself benefits from diffuse light; If an object is reflected by a mirror, we can only see the light source from it, but can't see the "true face" of the object, such as a mirror. If there is no reference object, then people can only see the image of the reflected light object, but they don't know what the mirror looks like. So the whole world we see is the diffuse light of objects, including the blackboard in the classroom, pleasing paintings, exquisite handicrafts and other typical examples. Without diffused light, we can't see these.