Looking at the tongue is a key step when looking at the face in TCM. Understanding the subdivisions of the tongue, and the relationship between the tongue and the internal organs, is important during facial diagnosis. The tongue is not only an organ for discriminating taste. It also has a close relationship with the internal organs in the body. The tongue is the organ of the heart and is the main blood vessel of the heart, so the tongue is rich in blood channels and is a manifestation of more blood and more qi. In general, the tip of the tongue reflects the pathology of the upper jiao, heart and lung, the middle of the tongue reflects the pathology of the middle jiao, spleen and stomach, the root of the tongue reflects the pathology of the lower jiao and kidney, and the sides of the tongue reflect the pathology of the liver and gall bladder. According to Chinese medicine, the tip of the tongue belongs to the heart and lungs, the middle of the tongue belongs to the spleen and stomach, the root of the tongue belongs to the kidneys, and the sides of the tongue belong to the liver and gallbladder. The tongue should be observed from the tongue texture, tongue coating, tongue buds and the vascular meridians at the base of the tongue. The tongue texture includes the size, shape, color, thickness, hardness and surface cracks; the tongue moss includes the color, moistness, thickness and the presence of moss spots; the vascular meridians at the base of the tongue are mainly observed in terms of length and thickness; the tongue buds are mainly looked at in terms of size and color.