<p>This series explores the areas of thermotherapy, mechanotherapy, electrotherapy, climatotherapy, and balneotherapy as well as light and phototherapy. These modalities are aimed at treating pain and functional limitations in the musculoskeletal system and all other organ systems, addressing limitations in mobility and participation. This article on phototherapy is a&#xa0;brief introduction to the subject of phototherapy. It does not claim to be exhaustive, but it is relevant to practical application.</p>