Photorejuvenation is a process involving the use of intense pulsed light (or other thermal or chemical methods) to treat some skin conditions and remove wrinkles arising from photoaging.

Photorejuvenation works by inducing controlled wounds on the skin, which prompts the skin to heal itself by creating new cells. This process reverses the effects of (photo-)ageing to a certain extent by removing wrinkles. (Source: Wikipedia.org)

Light Amplification by Stimulated Emission of Radiation (LASER or laser) is a mechanism for emitting electromagnetic radiation, typically light or visible light, via the process of stimulated emission. The emitted laser light is (usually) a spatially coherent, narrow low-divergence beam, that can be manipulated with lenses. In laser technology, "coherent light" denotes a light source that produces (emits) light of in-step waves of identical frequency, phase,[1] and polarization. The laser's beam of coherent light differentiates it from light sources that emit incoherent light beams, of random phase varying with time and position. Laser light is generally a narrow-wavelength electromagnetic spectrum monochromatic light; yet, there are lasers that emit a broad spectrum of light, or emit different wavelengths of light simultaneously. (Source: Wikipedia.org)