The Yin Yang is the Taoist symbol of the interplay of forces in the universe. In Chinese philosophy, yin and yang represent the two primal cosmic forces in the universe. Yin (moon) is the receptive, passive, cold female force. Yang (sun) is masculine- force, movement, heat. The Yin Yang symbol represents the idealised balance of the forces; equilibrium in the universe.
In my ring of symbols - an attempt to focus on links and similarities rather than differences. it follows the Zen Enso. The link between them is that the Zen school of Buddhism adopted precepts from Taoism.