Low Level Laser Therapy (LLLT) is one of the optical techniques applied to the treatment of different pathologies. LLLT is based on the photo-chemical and biological effects induced in cells and tissues when they are irradiated by an optical source. In this work we present the basic aspects of this technique and its applications, as long as the influence of the optical source parameters on the LLLT treatment. The choice of parameters like power, energy or exposition time allows light to reach different tissue depths. As a consequence the optical treatment can be adapted to the particular pathology we are dealing with
