The Tao is central to all Chinese philosophy and religion. It is often translated as the "way" or "path" - or the way of all things. The symbol that most accompanies it is the yin/yang symbol because the polarities of yin and yang form its essence and dynamism. Click below to the Yin and Yang page for more explanation of this.
The Tao is the Supreme Ultimate in Chinese religion. It is not a being or a god - it is higher, deeper, and infinite compared to any deities or such beings. It can be described variously as the force or power of all things, the cosmic force in all reality, the life source - and so on. All things derive from it and return to it. Everything has its existence within it. It is subtle, but ever-present; it is transcendent, but completely immanent in all things. Thus, it is paradoxical in nature.
The first line of the most important text in Taoism expresses the difficulty in describing or defining the supreme ultimate. "The Tao that is said to be the Tao is not the Tao; the Name that is said to be the Name is not the Name."
In other words, we cannot describe it in language. It cannot be reduced to words or concepts - it is infinite, mysterious, and exceeds all words no matter how poetic. So, when we describe or define it, we are merely approximating it - not encapsulating it in its essence or totality. Thus, we cannot become rigid or dogmatic about it, its qualities, nature or workings. We cannot know it intellectually or analytically; however, we can discern or intuit its presence and workings by developing certain virtues within us and following certain practices in our lives.
Confucianism and Taoism offer complimentary, and often opposing, methods for living in harmony with the Tao; however, both agree that there is no harmony outside it. There is no existence at all outside it.