What is the process called that occurs only in liquids or gases and involves the movement of matter and heat?

The process that occurs only in liquids or gases and involves the movement of matter and heat is known as convection. This phenomenon occurs when warmer, less dense fluid rises and cooler, denser fluid sinks, creating a circulation pattern that facilitates the transfer of thermal energy.

In convection, the movement of the fluid itself plays a crucial role in transporting heat from one location to another. As the fluid heats up, it becomes less dense and rises, while the cooler fluid sinks to take its place, creating a continuous flow that distributes heat. This is commonly observed in everyday situations, such as boiling water or the circulation of air in a heated room.

In contrast, conduction is the transfer of heat through a solid material without the movement of the material itself, and radiation involves the transfer of heat through electromagnetic waves, which does not require a medium like a liquid or gas. Insulation typically refers to materials used to prevent heat transfer but does not constitute a method of heat movement. Thus, convection accurately describes the process specified in the question.