Ambient Occlusion

Ambient occlusion is a self-shadowing effect that occurs at the intersection of two or more surfaces. The smaller the angle between the surfaces, the more shading occurs. Occlusion gives a more realistic look to the scene due to the self-shadowing of objects.

AOC map allows you to add realism to the image/reflection on the object by simulating the shadows on the material.

AOC map is responsible for the shading that occurs at the joints, faces and corners of the object. It defines the occlusion strength of the material.