Video: Laser hair removal might be the most requested cosmetic procedure, but how does it work? As Veritasium explains, dark hair contains melanin, a pigment that helps protect us from the sun by absorbing many wavelengths of visible and ultraviolet light. Bursts of high-energy laser light are absorbed much better by these unwanted hairs than by the surrounding skin, and the hairs start to increase in temperature when the laser hits them. Like popcorn, moisture inside the hairs evaporates rapidly which makes them look a bit... crispy.
Once they hit 60C or so, the hairs becomes irreparably damaged — cellular bonds start to break down in a process called denaturation. Cause enough damage and those hairs can't grow back. And remember, this all takes place in a split second.
Up closer and slowed day down, it's hard not to feel bad for the tiny hairs you just cooked.