The word "laser" stands for "light amplification by stimulated emission of radiation." Therapeutic lasers utilize a wavelength of monochromatic light in the 630 to 905 nanometer (nm) range, known as the “therapeutic window”. A wavelength of 905 nm has the least absorption in this “therapeutic window”, due to the primary influence of melanin. In the 630 to 905 nm range, the 905 nm wavelength is absorbed least by the skin and hence provides the greatest penetration of photons into the underlying tissues.