In Chinese philosophy, yin and yang describe how opposite or contrary forces are actually complementary, interconnected, and interdependent in the natural world, and how they give rise to each other as they interrelate with one another.
The original concept of YIN and YANG came from the observation of nature and the environment. “YIN” originally referred to the dark side of slop while “YANG” referred to the sunny side. Some examples include sky and earth, day and night, water and fire, active and passive, male and female, and so on.
Usually, Yang is associated with the functional aspect of an object and has more energetic qualities like moving, ascending, expanding, heating, bright, progressing, and active. On the other hand YIN is has less energetic qualities such as stillness, descending, cold, and darkness.
Duality is found in many belief systems but Yin and Yang are parts of Oneness. Yin and yang can be thought of as complementary (rather than opposing) forces that interact to form a dynamic system in which the whole is greater than the assembled parts. Everything has both yin and yang aspects, (for instance shadow cannot exist without light).
Either of the two major aspects may manifest more strongly in a particular object, depending on the criterion of the observation. The yin yang shows a balance between two opposites with a portion of the opposite element in each section.