This document discusses hot and cold applications for physical therapy. Hot applications above skin temperature are used to relieve pain and congestion, provide warmth, promote healing, and decrease muscle tone. Cold applications below skin temperature are used to reduce pain, body temperature, anaesthetize areas, control hemorrhaging and bacteria growth, and reduce inflammation. Both are classified as local or general dry heat/cold and moist heat/cold. Each has specific temperature ranges, physiological effects, contraindications, and potential complications.