Cold is a term used in traditional Chinese medicine, which mainly has the characteristics of cold, stagnation and collection. 1. Cold: Cold is the manifestation of yin qi, so the cold evil is also known as yin evil, cold for its primary characteristics, and feel the cold evil, the most easy to damage the body’s yang qi, thus appearing yang qi decline of cold evidence. 2. stagnation: that is, condensation blockage, refers to the cold evil attack on the human body, easy to make the human body qi, blood and fluid condensation, meridian blockage, mainly with the cold evil invasion of the body’s yang qi damage, the loss of warmth related. 3. Collected: so that the cold evil invasion of the human body, can make the human body qi convergence, coupling (Chinese medicine refers to the surface of the muscles, muscles, organs between the gap and texture), meridians, tendons, etc. contraction, constriction (due to the feeling of cold and the body body spasm, convulsions). Cold is the main gas of winter, if the cold is too much, injury to disease is cold, its invasion of the human body caused by the disease, is known as the external cold disease.