Heat transfer is the exchange of thermal energy (heat) in between two objects or along a single object.

There are different mechanisms of heat transfer. Conduction is the transport of thermal energy in between two objects that are in contact. This happens when a cooking pan is in contact with the hot surface of an electric stove. The metal of a pan is a good thermal conductor that transports the heat via conduction from the stove to the food in the pan.

Convection is the transport of heat through the movement of a liquid or gas. If you are holding your hand over a campfire, you can feel the heat of the fire. This heat is mainly transported through convection of the air. The air right next to the fire warms up, starts to rise, and transports the heat to your hands. The last process of heat transfer is radiation. In a glowing red metal, the atoms are moving fast. This movement creates electromagnetic radiation that transports heat to another object. The atoms of the second object are starting to move faster when being hit by the radiation and this results in a temperature increase of this object. Electromagnetic radiation itself is invisible but is constantly surrounding us. For example, it is used to transport music from a radio station to a car, or heat up food in the microwave.