What does Yin-Yang mean?

Yin and yang are complementary opposites. Whenever you observe a system that oscillates between two extremes, you are witnessing yin and yang at work. Whenever you see two interrelated parts that form a whole, that is yin-yang. Nature has countless examples of this principle. The seasonal cycle goes from maximum heat in summer to minimum heat in winter. Electromagnetic waves oscillate between maximum and minimum field strengths. Even subatomic particles can show yin and yang qualities. The electron is the yin particle; it is relatively weightless and has a negative charge. The proton is the yang particle; it is very massive, or full, and has a positive charge. They have opposite charges and are thus drawn to each other. Together, they form a complete, neutral atom. Fused into one particle, they become the neutron, the wuji particle. Wuji means perfect balance or stillness, when yin and yang have combined and neutralize each other. Thermodynamics is a good example of this. Given enough time, a concentration of heat (yang) will spread to cool areas (yin) until there is uniform temperature everywhere (wuji). This is how the universe works. Yin and yang originated from Daoist efforts to find patterns and cycles in nature. Categorizing things into either yin or yang is not as important as recognizing the dependence between the two. Think about the balance rather than the labels. The yin-yang symbol, also called the taijitu, shows how yin and yang form an endless cycle. Below are some examples of yin and yang.

Yang	Up	Outward	Full	Hard	Push	Male	Positive	Hot
Yin	Down	Inward	Empty	Soft	Pull	Female	Negative	Cold