A gentle beam of light is pulsed onto the skin and is absorbed by the pigment in your hair. Similar to how a dark shirt absorbs sunlight, the pigment in your hair also absorbs light and converts it into heat.
When heated sufficiently, the stem cells that line the hair follicle are disabled and prevent the hair from ever returning.
The darker and thicker the hairs are while the lighter or fairer the skin is will lead to more favourable results. This is because the energy from the laser is only absorbed by the hair and not by the skin. Clients with darker skin will still experience a reduction in hair but will need additional treatments to ensure their safety.