"Dry" refers to heavenly stems, and there are ten kinds, namely, A, B, C, D, Xu, Ji, Geng, Xin, Ren and Gui.
"Zhi" refers to "earthly branch", including twelve: Zi, Ugly, Yin, Mao, Chen, Ji, Wu, Shen, You, Xu and Hai.
Heavenly stems and earthly branches collocates one word each, and collocates in sequence, that is, from Jiazi, Emei ... to Guihai, which is exactly 60 groups in a cycle. Therefore, it is called "sixty flowers".
The lunar calendar invented in ancient China, also known as the official calendar, records the year, month, day and hour with "sixty flowers", thus recording a person's birth time. Year, month, day and hour each have the word "dry branch", which adds up to eight words, commonly known as "birthday".