TCM rests on seven basic criteria used to assess each patient’s overall condition :yin and yang(阴阳)for his or her constitution ; hypofunction (虚寒)for the level of body energy ;heat and cold(寒热)for the character of the disease based on subjective feelings of heat(fever)and cold(chills);exterior and interior(表里)for the body ;s area showing symptoms : Qi(气；vital energy),xue(血；blood)，and sui（水；water）for the body’s overall homeostatic balance ;the theory of the pathogenesis of visceral diseases （脏腑理论），and the six stages of disease (六经理论).these are explained in depth in later sections.|
In contrast , TCM is grounded on the theory of yin-yang and the five elements .The yin-yang theory interprets all materials and phenomena as the contrasting results of two opposing abstractions :yin and yang. The theory of five elements aims to categorize these entities in terms of the five elements wood (木) ，fire（火）, earth (土) ，metal （金） and water (水).
Wood corresponds to hepatic function(肝),fire to the heart or circulatory and autonomic nervous functions(心),earth to spleen and digestive function(脾)，metal to lung function(肺)，and water to kidney and urogenital function(肾).Using the above rationale , TCM explains physiology and the state of viscera(臟象)（the five parenchymatous viscera and the six hollow viscera）,qi/xue/shui(气/血/水)，meridians（经络；the circulation pathways of 气/血/水），etiology（病因），determinants of whether disease will arise(发病)，and pathological mechanisms(病机)in a unified manner.
Etiology consist of the six exogenous factors(六淫;wind,cold,heat,dampness,dryness,and fire),
the seven emotions（七情；joy,angry,anxiety,worry,grief , apprehension , and fear）,diet(饮食)，over-fatigue and under –exercising(劳逸)，exogenous pathogenic factors(外伤)，and diseases due to pathological accumulation of fluids in the body(痰饮).
The concept of pathological mechanism(病机)is further developed based on the concept of qi-related pathogenic factors(邪气盛衰),misbalanced yin-yang(阴阳失调).qi and xue disorders(气血失常),metabolic disorders of bodily fluids(津液代谢失常),and disordered yin-yang and qi xue in the five parenchymatous viscera(五脏的阴阳及气血的失调).