有啲曆法會定義特定嘅日期，例如農曆就會針對季節嘅變化，係太陽年入面選出二十四個日期，定為二十四個節氣。
Some calendars define specific dates, such as the lunar calendar, which selects 24 dates in a solar year and designates them as 24 solar terms in response to the change of seasons.