What is Earthly Branches?

A cycle of twelve characters (子丑寅卯辰巳午未申酉戌亥) that form the Chinese zodiac and underpin the traditional calendar. Each branch carries a Five Element and corresponds to an animal, a compass direction, and a two-hour period of the day. In Liu Yao, the month and day branches determine line strength. In the almanac, branch interactions govern date selection.

Source: Jingshi Yizhuan (京氏易傳), Jing Fang