Yao
The fundamental unit of a trigram, divided into yin yao and yang yao. Three yao form one trigram, and six yao form a hexagram.
A yao is the most basic unit composing a hexagram's image, divided into yang yao (a solid line) and yin yao (a broken line). Three yao stacked from bottom to top form a basic trigram (also known as a pure trigram), i.e., one of the Eight Trigrams. When two basic trigrams are placed one above the other, they form a six-yao hexagram, representing one of the 64 hexagrams. When interpreting the hexagram, the position of each yao, its yin/yang nature, and its relationship with other yao are all crucial for determining auspiciousness and the trend of events.