What is the purpose of purchasing thermal conductive silicone film?

What is the purpose of purchasing thermal conductive silicone film? Now Xiaobian tells you that the main purpose is to reduce the contact thermal resistance between the heat source surface and the contact surface of the radiator.

Thermal conductive silicone film can fill the gap of contact surface very well, and extrude air out of contact surface. Air is a bad conductor of heat, which will seriously hinder the transfer of heat between contact surfaces. With the supplement of thermal conductive silicone film, contact surface can be better fully contacted and face-to-face contact can be achieved. Reaction at temperature can achieve as little temperature difference as possible.