Yin and yang is represented by two fundamental forces which create the Universe and bring it into harmony by the interaction and continuous search of balance. These two opposite, clashing forces are present at each action. They symbolize two opposite to energy which, changing and interacting, represent dynamics of the world. It is a symbol says that the reality consists of interaction of contrasts and opposite principles.
Yin and yang depend from each other, create the constant movement, rising and falling as waves, and maintain mutual harmony.
Not only are opposite to yin and yang, but also harmoniously supplement each other.