What is the term for the direct transfer of heat from one substance to another substance that is touching?

Conduction is the term that describes the direct transfer of heat between two substances that are in physical contact with each other. This process occurs at the molecular level as kinetic energy is passed from one molecule to another when they collide. For example, when a metal spoon is placed in a hot cup of coffee, the heat from the coffee is transferred to the spoon through conduction, making the spoon hot over time.

In contrast, convection involves the transfer of heat through the movement of fluids (liquids or gases), where warmer areas of a fluid rise and cooler areas sink, creating a circulation pattern. Radiation refers to the transfer of heat in the form of electromagnetic waves, such as the warmth felt from sunlight, which does not require a medium to transfer heat. Insulation, on the other hand, relates to materials that reduce the rate of heat transfer, rather than the transfer itself. Thus, conduction accurately defines the direct transfer of heat through contact between substances.