The Yin and Yang: opposites attract!
What are Yin and Yang?
Yin and Yang notions are two opposite and complimentary states of the universal energy, the Chi. While the Yang is action, movement, masculine, hot and bright; the Yin is stillness, receptive, feminine, cold and dark.
Are they to be considered as the classic opposition of good vs evil?
There is no positive or negative aspect attached to those two notions. They are the two sides of a coin, necessary and complimentary. Without shadow, there is no light, and vice-versa.
Are they static?
Not really. The Yin and Yang are always in movement, there are parts of a cycle. There is always a little bit of Yin in the Yang and vice-versa, as expressed by the Tai Chi symbol.
How to use them in Feng Shui?
Yang and Yin energies are a fundamental part of Feng Shui: there are considered to be one of the three factors in San Yuan Feng Shui The forces of Yin and Yang are used to balance the energy of a place, and make it perfectly suitable for human occupancy. For example a bedroom should not be too Yang or it will disturb the sleep pattern.
In a business Yin and Yang notion are also used to balance the whole setup. For example the cash machine should be on a Yang side where the energy is more active. The main door should ideally be on a Yang sector as well. Yang and Yin are everywhere in Chinese metaphysics; in Feng Shui, in oracle, in oracles such as Qi Men Dun Jia or in Bazi.