The first lasers used to treat skin conditions occurred over 40 years ago. Argon and carbon dioxide (CO₂) lasers were commonly used to treat benign vascular birthmarks such as port-wine stains and haemangiomas. Although these birthmarks could be effectively lightened, a side effect was the unacceptably high rate of scar formation.

In the last 20 years major advances in laser technology has revolutionized their use in the treatment of many skin conditions and congenital defects, including vascular and pigmented lesions, and the removal of tattoos, scars and wrinkles. Nowadays there is a wide spectrum of laser and light technologies available for skin resurfacing and rejuvenation.

Lasers are sources of high intensity light with the following properties:

• Monochromatic, i.e., the light is of a single wavelength
• Coherent, i.e., the light beam waves are in phase
• Collimated, i.e., the light beams travel in parallel