Ci is the mainstream of literature in Song Dynasty. The form of ci appeared in the Tang and Five Dynasties, but it matured in the Song Dynasty. The original feature of words is that they can be sung with poems and tunes. Each word has a title called "epigraph", and the lyrics written according to the title are called "Eternal Sound". Song Ci also has the titles of Qu, Zaqu, Quzi Ci, Yuefu, Qinqu, Music Movement, Long and Short Sentences, etc. Because of the different rhythms, it is divided into sequence, introduction, approach and slowness. Ling is still a small ling, and the slow word is also a long tune. Words are generally divided into two segments (called upper and lower segments or upper and lower segments), and there are few words that are not divided into two or more segments. Many literati in Song Dynasty liked to write lyrics, which played an important role in promoting the development of lyrics. The writers, works and quality of Ci in the Song Dynasty are far ahead of their predecessors, becoming another influential literary genre after Tang poetry. The words of later generations are generally not sung and basically become a literary form.