to a broad spectrum of light,
the varieties of which are intended to obliterate the ink in the tattoo without damaging the skin.
Certain colors of light are absorbed by specific corresponding colors of the tattoo ink. The light energy vaporizes or fragments the ink particles. Your body then absorbs these ink fragments naturally and the color fades over the next couple of weeks.
The newest lasers for this, known as Q-switched lasers, are specifically useful for tattoo removal.