风筒又称吹风机是在19世纪末发明。现代风筒以电动方式加速空气流动速度，故产生风，并同时提高空气温度的机械设备。大部分的风筒都会经过发热线吹出热风，加速水份蒸发，而冷风则对头发的伤害相对地小。

吹风机吹出来的风，是携带提高动能的空气分子，在碰撞微小水珠表面的水分子的过程中转移动能，使之打断水分子之间的氢键，脱离原本附着的表面(即蒸发)，头发因而变干。如吹出的是热风，其能量更能提高空气分子与水分子震荡与碰撞的能量，并加速蒸发，所以增加干燥的效率。

A blow dryer or hair dryer is an electromechanical device designed to blow normal or hot air over damp hair, in order to accelerate the evaporation of water particles and dry the hair. Blow dryers allow better control over the shape and style of hair, by accelerating and controlling the formation of temporary hydrogen bonds inside each strand. These hydrogen bonds are very powerful (allowing for stronger hair shaping than even the sulfur bonds formed by permanent waving products), but are temporary and extremely vulnerable to humidity. They disappear with a single washing of the hair.