Basically, the IPL light is attracted to the pigment in the hair. The point of IPL is to shrink the hair follicle in which the hair sits, so that the hair can’t grow any longer. The real plus is it is Pain Free.
IPL is non monochromatic (not a single wavelength) and non-focused, treats multiple follicles at once, and is attracted to varying degrees of hair colour.
IPL covers a larger area per pulse of light therefore making the process faster and with the added benefit of seeing many shades of colour.