This graduate thesis explains the basic laser principles and provides an overview of indications for laser treatment in dermatology. The term laser is an acronym for light amplification by the stimulated emission of radiation. Since the development of first laser by Maiman and the introduction of theory of selective photothermolysis in 1980 by Anderson and Parish, it gained widespread acceptance in dermatology and is now used for the treatment of numerous cutaneous conditions including pigmented and vascular lesions, tattoos, scars, unwanted hair, and aging skin. When a laser is used on the skin, the light can be absorbed, reflected, transmitted or scattered. Once laser energy is absorbed, the possible effects are photochemical, photothermal and photoacoustic. Due to different clinical applications of wavelengths and pulse durations, the choice of laser should be based upon the individual absorption characteristics of the target chromophore. Pigment specific lasers target melanin and can successfully lighten or eradicate a variety of benign epidermal and dermal pigmented lesions and tattoos with minimal risk of unwanted effects. Nowadays, Q-switched lasers are the first choice for most pigmented lesions, but continuous wave and quasi-continuous wave lasers can also be effective if used properly by experienced operator. Laser systems for hair removal include alexandrite (755 nm), diode (800 and 810 nm) and Nd:YAG (1064nm). Vascular specific laser systems target intravascular oxyhemoglobin to destroy congenital and acquired vascular lesions. Lasers used for this purpose include PDL (585 nm), long pulsed-dye laser (595 nm), KTP (532 nm) and the Nd:YAG (1064 nm). CO2 and Er:YAG lasers were traditionally used for laser skin resurfacing, but one of the newest trends in dermatology has been development of nonablative and fractional laser systems whose advantages are less side effects and decreased downtime. Of outmost importance is the safety of both patient and the operating room personnel during laser irradiation. Key safety measures include education, eye, skin and teeth protection, as well as protection from plume, fire and electrical hazards.