Heat transfer: The process of transferring heat from one object to another, or from one part of an object to another, under the condition of no work but only temperature difference is called heat transfer.

Heat transfer modes: conduction, convection and radiation.

Heat conduction: heat transfer from high temperature to low temperature caused by the thermal motion and interaction of molecules or atoms that make up the system.

Thermal convection: The process in which a fluid relies on its macroscopic flow to realize heat transfer is called thermal convection.

Thermal radiation: the way to transfer energy through electromagnetic waves is called thermal radiation. It has a continuous radiation energy spectrum with a wavelength extending from the far infrared region.