In this section, the biological importance of body temperature, pulse, respiratory rate, mucosal examination, and elasticity concepts known as vital signs, especially temperature, is evaluated, with an emphasis on fever and its types. Information about thermometers is given, and the relationships between thermoregulation, thermotherapy, cauterization, and sunlight and the basic areas of therapy were emphasized. The Wien Shift Law and radiation band are examined, and the wavelengths of larger and smaller rays outside the visible region, which are biologically important, were examined. In particular, the hydrogen series are classified and the concepts of brightness and luminosity are explained. Information was given about air therapy, another method used in veterinary medicine. At the end of each section, the subject is detailed with explanatory questions.