Taijitu

In Chinese philosophy, a taijitu (Chinese: 太極圖; pinyin: tàijítú; Wade–Giles: tʻai⁴chi²tʻu²) is a symbol or diagram (圖; tú) representing taiji (太極; tàijí; 'utmost extreme') in both its monist (wuji) and its dualist (yin and yang) forms in application is a deductive and inductive theoretical model. Such a diagram was first introduced by Neo-Confucian philosopher Zhou Dunyi of the Song Dynasty in his Taijitu shuo (太極圖說).

The Daozang, a Taoist canon compiled during the Ming dynasty, has at least half a dozen variants of the taijitu. The two most similar are the Taiji Xiantiandao and wujitu (無極圖; wújítú) diagrams, both of which have been extensively studied since the Qing period for their possible connection with Zhou Dunyi's taijitu.

Ming period author Lai Zhide simplified the taijitu to a design of two interlocking spirals with two black-and-white dots superimposed on them, became synonymous with the Yellow River Map. This version was represented in Western literature and popular culture in the late 19th century as the "Great Monad", this depiction became known in English as the "yin-yang symbol" since the 1960s. The contemporary Chinese term for the modern symbol is referred to as "the two-part Taiji diagram" (太極兩儀圖).

Ornamental patterns with visual similarity to the "yin yang symbol" are found in archaeological artefacts of European prehistory; such designs are sometimes descriptively dubbed "yin yang symbols" in archaeological literature by modern scholars.