Tao or Dao is a Chinese word meaning 'way', 'path', 'route', or sometimes more loosely, 'doctrine' or 'principle'. Within the context of traditional Chinese philosophy and religion, Tao is a metaphysical concept originating with Laozi that gave rise to a religion (Wade–Giles, Tao Chiao; Pinyin, Daojiao) and philosophy (Wade–Giles, Tao chia; Pinyin, Daojia) referred to in English with the single term Taoism. The concept of Tao was later adopted in Confucianism, Chán and Zen Buddhism and more broadly throughout East Asian philosophy and religion in general. Within these contexts Tao signifies the primordial essence or fundamental nature of the universe. In the foundational text of Taoism, the Tao Te Ching, Laozi explains that Tao is not a 'name' for a 'thing' but the underlying natural order of the universe whose ultimate essence is difficult to circumscribe. Tao is thus "eternally nameless” (Dao De Jing-32. Laozi) and to be distinguished from the countless 'named' things which are considered to be its manifestations.

Cao is the pinyin romanization of the Chinese surname  (Cáo).

Tao is a metaphysical concept found in Taoism, Confucianism, and more generally in ancient Chinese philosophy.