In Ancient Chinese philosophy, yin and yang is a concept of dualism, describing how seemingly opposite or contrary forces may actually be complementary, interconnected, and interdependent in the natural world, and how they may give rise to each other as they interrelate to one another. Yin and Yang are two different words with completely opposite meaning. If Yin is negative/dark then, Yang is positive/bright. Yin Yang together maintains harmony of the universe and influences everything within it.
Source: Wikipedia
