Qi is a common concept in China's philosophy, Taoism, Chinese medicine and China Qigong. Qi, the basic category of China's ancient philosophy, is a moving and subtle material entity, the most basic element of all things in the universe, the origin of the world, and an objective existence that marks the occupation of space and can move. Qi is China's shallow understanding of the origin of the world in ancient times, which covers everything from cloud gas and water vapor to quantum and field, and can be described as "nothing is bigger" and "nothing is smaller".
Meridian is the only unique theory invented by China in world medicine. It does not depend on drugs, but plays a role in regulating the qi of meridians. According to the meridian theory, the qi of human viscera can be perfused through meridians, and the corresponding parts can be found on the body surface. These parts are not isolated from the body surface, but communicate with the qi of internal organs. The exterior is mostly a depression between limbs, muscles or bones. Because the internal and external qi are functionally interlinked and mainly located in pores, it is called "acupoints". The network structure between acupoints is composed of meridians and their subsidiary parts, which is connected with the qi of internal organs and formed regularly and coherently.