Literally,qi means air. Philosophically, qi is the prime element of the universe, according to the ancient thought. it is the changes and movement of qi that produce all the phenomena of the universe. In theories of Chinese medicine, which is greatly influenced by ancient thought, qi can be translated as "life force."Qi within the human body is invisible, but it is manifested by the functions of the body organs.
Qi extends to all parts of the body and determines every part's well-being. Abundance of qi is the basis of good health and weakness of qi may lead to diseases.
There is a close relationship between qi and blood.