As a dermatologist, it is necessary to have some knowledge about the principles of phototherapy and photochemotherapy. Thus, these treatments can be used more effectively. It does not mean that dermatologists should know more details as a photobiologist or an engineer. However, some knowledge may provide “a good clinical practice” in the patient management. In this section, ultraviolet radiation sources, dosimetry and some answers about photo(chemo)therapy questions have been evaluated trying to “not boring” to the readers
