Define 'thermal conductivity' in the context of materials.

Thermal conductivity is fundamentally defined as the measure of a material's ability to conduct heat. It quantifies how easily heat can pass through a material when there is a temperature difference across it. High thermal conductivity indicates that a material can transfer heat efficiently, making it suitable for applications where heat dissipation is required. For instance, metals typically have high thermal conductivity, while insulating materials like foam have low thermal conductivity because they resist the flow of heat.

Understanding this concept is crucial, particularly in fields such as engineering and materials science, where the efficiency of thermal management in systems is vital to their performance and reliability.