电风扇，日本和韩国称为扇风机，现代风扇以电为能源，故又称电风扇，简称电扇，台语称为电风。风扇是一种通过驱动扇叶旋转，来达到使空气加速流通的机械，主要用于清凉解暑和空气流通。电风扇则是电力来驱动扇叶旋转来达到使空气加速流通的家用电器。

风扇这种机械历史悠久，中国西汉时长安有名的机械师丁缓发明了七轮扇，这大概是在一个轮轴上装有7个扇轮的风扇，以人力推动机轮运转。使人感到凉爽主要原理是驱动扇叶旋转，加速人体周围空气流通，人体从皮肤上毛孔蒸发水分的速度加快了，由于水分蒸发过程所带走的热量增多，人感到凉爽。

A fan is a machine used to create flow within a fluid, typically a gas such as air. The fan consists of a rotating arrangement of vanes or blades which act on the fluid. The rotating assembly of blades and hub is known as an impeller, a rotor, or a runner. Usually, it is contained within some form of housing or case. This may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines. Fans produce flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to a fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan.