The Bagua or Pa Kua are eight symbols used in Taoist cosmology to represent the fundamental principles of reality, seen as a range of eight interrelated concepts. Each consists of three lines, each line either «broken» or «unbroken», respectively representing yin or yang. Due to their tripartite structure, they are often referred to as «trigrams» in English.

The trigrams are related to Taiji philosophy, Taijiquan and the Wu Xing, or «five elements».[1] The relationships between the trigrams are represented in two arrangements, the Primordial (先天八卦), «Earlier Heaven»[2] or «Fu Xi» bagua (伏羲八卦), and the Manifested (後天八卦), «Later Heaven,»[2] or «King Wen» bagua. The trigrams have correspondences in astronomy, astrology, geography, geomancy, anatomy, the family, and elsewhere.[3][4]

The ancient Chinese classic, I Ching (Pinyin: Yi Jing), consists of the 64 pairwise permutations of trigrams, referred to as «hexagrams», along with commentary on each one.