**3. History**

The term "LLLT" is broadly applied to the therapeutic effects of lasers; other terms, such as low power laser therapy, laser biomodulation, laser bioactivation, laser biostimulation, laser irradiation, and laser photostimulation, may be substituted for LLLT. In this review, the author have chosen the term LLLT photostimulation because of the observed stimulatory effects of the laser beam and photochemical nature of its interaction with biological systems. LLLT is a special type of laser that influences biologic systems through nonthermal means [2]. The use of LLLT as a therapeutic modality has originated from Eastern Europe approx‐ imately 50 years ago [2]. In 1967, Professor Mester, an employee of Semmelweis University in Budapest, Hungary, observed that applying laser light to the shaven backs of mice could cause more rapid regrowth of hair compared to unshaven mice [3]. He reported that the helium‐neon (He‐Ne) laser had the capability to promote wound healing in mice [4]. Professor Mester applied these findings to humans when he used lasers to treat patients with nonhealing skin ulcers [5, 6]. The clinical applications of LLLT have become the leading edge of clinical research in several countries, such as the former USSR, Japan, Canada, Australia, United Kingdom, China, and several Scandinavian countries. The history, origin, and development of various lasers are well authorized [2]. The clinical application of laser photobiostimulation is growing rapidly. Several review articles that explain the clinical applications of LLLT have been published [2]. LLLT is currently considered not only as a therapeutic procedure primarily used for relief of inflammation, edema, and chronic joint disorders; escalate healing of the wounds, deeper tissues, and nerves; but also as a treatment for neurological disorders and pain [7].
