All bodies with a temperature greater than absolute zero emit heat in the form of electromagnetic radiation, which is absorbed by other bodies at lower temperatures. A black body is an ideal body that absorbs all the radiation that falls on it and reflects nothing; thus, the surface appears black. Black holes are very close to an ideal black body; they absorb all the radiation entering the horizon and reflect nothing. On the contrary, a reflector is that ideal body, which reflects all the radiation and absorbs none of it. For example, when a car is parked in summer, foldable pads with silver or aluminum coating are used as a reflector to keep the car cool. Further, out of all the radiation emitted by the Sun, some are absorbed by greenhouse gases like water vapor, carbon dioxide, and methane present in the Earth's atmosphere. This radiation is then re-emitted in all directions, keeping the Earth warm. This phenomenon is called the greenhouse effect, which prevents Earth from freezing and making life on Earth possible.