The Rat or Mouse (鼠) is the first of the repeating 12-year cycle of animals which appear in the Chinese zodiac, constituting part of the Chinese calendar system (with similar systems in use elsewhere). The Year of the Rat in standard Chinese is Chinese: 鼠年; pinyin: shǔnián. The rat is associated with the first branch of the Earthly Branch symbol 子 (zǐ), which starts a repeating cycle of twelve years.
The Chinese word shǔ (鼠) refers to various small rodents (Muroidea), such as rats and mice. The term "zodiac" ultimately derives from an Ancient Greek term referring to a "circle of little animals". There are also a yearly month of the rat and a daily hour of the rat (Chinese double hour, midnight, 11:00 p.m. to 1:00 a.m.). Years of the rat are cyclically differentiated by correlation to the Heavenly Stems cycle, resulting in a repeating cycle of five years of the rat (over a sixty-year period), each rat year also being associated with one of the Chinese wu xing, also known as the "five elements", or "phases": the "Five Phases" being Fire (火 huǒ), Water (水 shuǐ), Wood (木 mù), Metal (金 jīn), and Earth (土 tǔ).
