Yin qi, opposite to yang qi, generally refers to one of the two components that are opposite and complementary to each other. In terms of function and form, it is form. In terms of visceral function, it is qi of five zang-organs. In terms of nutrient qi and defense qi, it refers to the former. In terms of the direction and nature of movement, it tends to be inward, downward, inhibitive, weak, and turbid. In short, yin qi refers to the qi in nature with the attribute of coldness, eliminating, astringency, turbidity, forming, and descending as well as the qi in human body with that of coolness, contraction, concentration, moistening, and suppression.