There are three modes of heat transfer namely conduction, convection and radiation.

Conduction : Conduction refers to the heat transfer that occurs across the medium. Medium can be solid or a fluid.

Convection : Convection refers to the heat transfer that will occur between a surface and a moving fluid when they are at different temperatures.

Radiation : In radiation, in the absence of intervening medium, there is net heat transfer between two surfaces at different temperatures in the form of electromagnetic waves.