So what is "Tao"?

The origin of the universe: Tao is the fundamental and source of the universe.
The law of nature: Tao is the operating law of nature.
The philosophy of life: Tao is a kind of life philosophy, advocating conforming to nature and governing by non-interference.
Ethics and morality: Tao involves ethics and morality, emphasizing virtue.
Cultivation practice: The goal of Taoist cultivation is to pursue and practice Tao.