散热片在电子工程设计的领域中被归类为「被动性散热组件」，以导热性佳、质轻、易加工之金属（多为铝或铜，银则过于昂贵，一般不用）贴附于发热表面，以复合的热交换模式来散热。

所谓的主动性散热、被动性散热是如何界定？主要是以需不需要额外的驱动能源才能运行散热来分别，散热片是最典型的被动性散热组件，除此之外热导管（heat pipe）也是近年来日益普及与推崇的被动性散热组件，至于主动式散热组件则有散热风扇（用马达、电力驱动）、水冷循环等。

为了强化散热片的散热效率，一般还会采取两个手段，一是与发热表面间不采行直接贴附接触，而是在两接面间追加涂抹「导热膏」，导热膏能够加强热传导效率，胜过两金属直接贴触，另一则是增加散热片的散热面积，增加面积的方式即是将散热片以沟**方式设计，以沟槽来增加散热面积。

A heat sink (also commonly spelled heatsink) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device into a coolant fluid in motion. Then-transferred heat leaves the device with the fluid in motion, therefore allowing the regulation of the device temperature at physically feasible levels. In computers, heat sinks are used to cool central processing units or graphics processors. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light emitting diodes (LEDs), where the heat dissipation ability of the basic device is insufficient to moderate its temperature.