Laser hair removal works by the laser targeting a group of hair follicles, using enough energy to disable and/or destroy the root without harming the surrounding skin.
This process is called selective photothermolysis (photo means light and thermolysis mean destroying with heat). It is selective because it targets only the hair and not the skin.
Hair is natural to your body and it grows in stages. At any given time, not all hairs are in the growth or active stage. Lasers are most effective at targeting active hairs, meaning hairs in the active stage. Some follicles are destroyed, while others are miniaturized into fine hairs or shocked into prolonged dormancy.
Multiple treatments are required for best results. The best interval for retreat depends on the hair cycle growth patterns in that area of the body. Age, ethnicity, weight, metabolism, medication, and hormones all play a huge role in the resilience, as does the thickness of the hair follicle.