Yin Yang is perhaps the most known and documented concept used within Taoism. In Chinese philosophy, yin and yang describes how seemingly opposite or contrary forces may actually be complementary, interconnected, and interdependent in the natural world.
Yin and Yang is two halves that together complete wholeness. Yin and yang are also the starting point for change. When something is whole, by definition, it’s unchanging and complete. So when you split something into two halves – yin/yang, it upsets the equilibrium of wholeness. Both halves are chasing after each other as they seek a new balance with each other.
The word Yin comes out to mean “shady side” and Yang “sunny side”. Yin Yang is the concept of duality forming a whole. We encounter examples of Yin and Yang every day. As examples: night (Yin) and day (Yang), female (Yin) and male (Yang). Over thousands of years, quite a bit has been sorted and grouped under various Yin Yang classification systems.
The two opposites of Yin and Yang attract and complement each other and, as their symbol illustrates, each side has at its core an element of the other (represented by the small dots). Neither pole is superior to the other.
Sources: personaltao.com, ancient.eu