What is Ying Yang’s concept that is used in TCM?

The concept of yin and yang is one of the central pillars of Chinese philosophy. It is a dualistic approach which holds that everything in the universe is inextricably linked and interconnected in a continuously cycling balance of two opposing forces. On the one hand, there is yin, the dark, cold, and feminine energy, and on the other yang, the bright, hot, and masculine energy. Together, these two forces work together to create balance and harmony. The key to understanding this concept is recognizing that nothing is ever entirely one or the other, but rather a constantly changing interaction between the two, much like a see-saw in perpetual motion. In this way things remain in balance, just as in the natural world.