Thermal or Heat energy transfer is the movement of heat from one object/substance to another. Usually it always flows from something warmer to something cooler until both reach the same temperature. 

Conduction happens when heat travels through direct contact between materials. The particles in the warmer object vibrate faster and collide with the slower-moving particles in the cooler object, passing on their energy 

In the image above, you can see the handle is getting warmer as the pot is getting heated from the stove.

Convection happens in liquids and gases, where warmer parts rise and cooler parts sink, this creates a circular motion called the convection current 

In the image above, the cool molecules are going down as the warmer molecules are going up, in turn showing "convection".

In radiation, heat is traveling through waves, not by touch or air. Energy is transferred through electromagnetic waves, mainly in the form of infrared radiation.

In the image above, if you were to place your hand near the fire, you wouldn't see it, but you would feel it. These are the waves your body would feel, making you warmer.

Thermal energy transfer is an essential process that balances our environment. It is used in cooking, weather systems, and can even be seen as how we regulate our body temperature. Understanding thermal energy transfer also helps scientists design better insulation, heaters, and cooling systems. It’s an essential part of our daily life.