Spring, summer, fall, and winter; delicate changes in temperature and climate of each season can be sensed all through the year in Japan. Traditionally Japanese people have relied on the nijushi (24)-sekki calendar, which is a system dividing the year into 24 periods. People have used this calendar to decide the dates of events in agriculture, politics, festivals, and so on. There are a lot of works in literature, music, and fine arts which are concerned with the seasons. In Kigo (season words) used in Haiku poems or some other literary works, particular words for weather conditions, animals, plants, natural phenomena, or social events indicate the season in which the work is set. The number of Kigo has still been increasing year by year. Most of the local events such as festivals, celebrations, and farm work are carried out in conformity with the seasons.