The document discusses hot and cold applications, including their purposes, mechanisms of action, effects on the body, indications, contraindications, potential complications, and best practices. Hot applications are used to relieve pain and congestion, provide warmth, promote healing and suppuration, and decrease muscle tone. Cold applications are used to reduce pain, temperature, control hemorrhage and bacteria growth, prevent gangrene and edema, and decrease inflammation. Both work through mechanisms like vasodilation/constriction and changes in blood flow, metabolism and viscosity. Contraindications include open wounds, malignancies and certain medical conditions. Complications can include burns, maceration, edema if not properly administered.