In Chinese metaphysics, Yin (阴) is one of the two fundamental principles that constitute the dualistic nature of existence, with the other being Yang. Together, Yin and Yang represent the concept of dualism and the interplay of opposites in the natural world. Yin is often associated with feminine qualities and characteristics. It represents receptivity, passivity, darkness, coldness, and contraction. This principle is essential for understanding the balance and dynamic interaction of energies in various aspects of life and the universe.