Ancient Chinese divided the circle of the annual motion of the sun into 24 equal segments; each segment was called a "jie qi" or solar term. Hence the 24 segments are collectively called the 24 Solar Terms. This system of time embodies the traditional knowledge and the social practices through which Chinese organize their perception of the regularity of seasons, of astronomical laws and of other local natural phenomena occurring in the course of the year. It is an indispensable component of the traditional Chinese calendars and its living applications, serving as a time-frame for agricultural activities and daily life.