Chinese herbal medicine uses well over 4000 species of medicinal plants, but its unique aspect is its philosophy, the way of thinking and the terminology based on more than 3000 years of clinical observation. It is not associated with any religious thought and is a traditional science. Increasing numbers of studies are showing the effectiveness of TCM. Traditional terms such as Yin and Yang, cold and warm, nourish and clear are used to describe the herbal properties. The medicine consists mostly of plant roots, while others of leaves, flowers, seeds and fruits.