Thermal grease (also called CPU grease, heat paste, heat sink compound, heat sink paste, thermal compound, thermal gel, thermal interface material, or thermal paste) is a thermally conductive (but usually electrically insulating) compound, which is commonly used as an interface between heat sinks and heat sources such as high-power semiconductor devices. The main role of thermal grease is to eliminate air gaps or spaces (which act as thermal insulation) from the interface area in order to maximize heat transfer and dissipation.