We know that light can move from one place to another ,it doesn’t required medium. Similarly the heat energy can also transmitted aslight, infrared radiation or another form of electromagnetic waves.As contact required for conduction and convection no contact is required for radiation.The best example of radiation is the sun heating the earth.This is a direct transfer of heat from one object to another, without heating the air in between.
The sun warms the earth without warming the space between the sun and the earth.
This energy coming from a hot body and it can travel freely only through completely transparent media. But the radiation cannot go through a solid object.
Materials like glass, translucent materials even atmosphere pass a significant amount of radiant heat.
In the given figure we can see the example of heat transfer.