A thermal infrared image of two coffee cups filled with a hot liquid. Notice how the heat from the drink has caused the cups to glow. The heat was transfered from the hot liquid to the cup by conduction. Conduction occurs when two object at different temperatures are in contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature.
Conduction is the movement of heat through a substance by the collision of molecules.
At the place where the two object touch, the faster-moving molecules of the warmer object collide with the slower moving molecules of the cooler object. As they collide, the faster molecules give up some of their energy to the slower molecules. The slower molecules gain more thermal energy and collide with other molecules in the cooler object. This process continues until heat energy from the warmer object spreads throughout the cooler object. Some substances conduct heat more easily than others.