This is an excerpt from taijizen.org, a school founded by Jet Li and Jack Ma. The site looks non-maintained, with latest posts in 2013. The facebook page looks current, though. Of course, the meaning of taiji stays the same.
Taiji 太极 is an ancient Chinese philosophy about the natural world and is one of the central elements of traditional Chinese culture.
The word Taiji itself refers to the “great primal beginning” of all that exists, and is often translated as the ‘Supreme Ultimate’. It is the state of absolute and infinite potential, the oneness before the duality. This concept is comparable to the initial state of the universe right at the moment of the big bang, or the initial singularity. From this state, Yin and Yang were generated.