Yin and Yang is the basis of Feng Shui teaching. The polarity of Yin to Yang is, for example, subdivided in the trigrams and hexagrams in finer quality stages. The meanings and attributions are described in the old Chinese I Ging (Book of Changes).
The Yin Yang symbol, however, basically represents the dynamics of the eternal processes of change (birth - growth – maturity – blossom – seeds – death ...).
The constant flux (change), and the movement are best represented in the symbol.