Cí (pronounced [tsʰɨ̌]; Chinese: 詞) is a type of lyric poetry in the tradition of Classical Chinese poetry. Cí use a set of poetic meters derived from a base set of certain patterns, in fixed-rhythm, fixed-tone, and variable line-length formal types, or model examples. The rhythmic and tonal pattern of the ci are based upon certain, definitive musical song tunes. They are also known as Changduanju (長短句 / 长短句, "lines of irregular lengths") and Shiyu (詩餘 / 诗馀, "the poetry is besides Shi").
Typically, the number of characters in each line and the arrangement of tones were determined by one of around 800 set patterns, each associated with a particular title, called cípái (詞牌). Originally, they were written to be sung to a tune of that title, with a set rhythm, rhyme, and tempo. Therefore, the title may have nothing to do with its content. Indeed, several ci often shared the same title. The titles did not refer to the content, but rather their shared rhythmic and tonal patterns. Some cí would have a "subtitle" or a commentary, sometimes as long as a paragraph, indicating the content. Sometimes, for the sake of clarity, a cí is listed under its title, followed by its first line.
Although the oldest surviving textual examples of cí are from 8th century CE Dunhuang manuscripts, beginning in the poetry of the Liang Dynasty, the ci followed the tradition of the Shi Jing and the yuefu: they were lyrics which developed from anonymous popular songs into a sophisticated literary genre. In the case of the cí form some of its fixed-rhythm patterns have influenced poetry in Central Asia.
The form was further developed in the Tang Dynasty. Although the contributions of Li Bai (701 – 762) are fraught with historical doubt, certainly the Tang poet Wen Tingyun (812–870) was a great master of the ci, writing it in its distinct and mature form. One of the more notable practitioners and developers of this form was Li Yu of the Southern Tang Dynasty during the Five Dynasties and Ten Kingdoms period.
However, the ci form of Classical Chinese poetry is especially associated with the poetry of the Song Dynasty, during which it was indeed a popular poetic form. A revival of the cí poetry form occurred during the end of the Ming Dynasty and the beginning of the Qing Dynasty which was characterized by an exploration of the emotions connected with romantic love together with its secularization, often in a context of a brief poetic story narrative within a cí poem or a linked group of cí poems in an application of the chuanqi form of short story tales to poetry.
In Song Dynasty, two main categories of cí employed were xiǎolìng 小令 (the original form since Pre-Song) and màncí 慢詞 (starting after Liu Yong), depending on the song being either short and in fast tempo or long and in slow tempo. Mostly xiǎolìng were written in Pre-Song era.
- xiǎolìng 小令 if it's no more than 58 characters,
- zhōngdiào 中調 for 59–90, and
- chángdiào 長調 for over 90.
If the ci appears in one stanza, it's called dāndiào (單調). The largest majority is shuāngdiào 雙調 with two stanzas or què 闋 in identical or nearly identical patterns. There also are rare cases of sāndié 三疊 and sìdié 四疊, for three and four qüè, respectively. In terms of style, cí can also be classified as either wǎnyuē 婉約 (grace) or háofàng 豪放 (bold).
According to Chinese Pronunciation, "Mandarin is said to have four main tones and one neutral tone (or, as some say, five tones). Each tone has a distinctive pitch contour which can be graphed using the Chinese 5-level system." 
The Wikipedia page on Old Chinese phonology states that "The four tones of Middle Chinese were first described by Shen Yue around AD 500. They were the "level" (平 píng), "rising" (上 shǎng), "departing" (去 qù), and "entering" (入 rù) tones." The level is classified in 平 ping; and the rising, departing and entering are classified in 仄 ze. So, in any Cipai, the formation of Ci, each Chinese character in Ci will be required in detailed tones with 平 or 仄.
Cipai, also called Cige and Cidiao, is the name of various formations of Ci. Most cípái consist of three characters. The literal meaning of a cípái can be rather obscure, making it difficult to translate. Some are taken straight from earlier poems, and some are clearly of Non-Han origin—mostly songs introduced from Central Asia. Some cípái have alternative names, usually taken from a famous piece of that very cípái. There also are variants of certain cípái, indicated by a prefix or a suffix. The formations of Ci are complicated, in different names of Cipai, the number of characters, syntactical structure, tones and rhyme are also different.
For example, choosing the Cipai, Jiang Chengzi or "Riverside City" (江城子), the tones requirement of each characters in this Cipai is following:
The following content is a cí poetry of 江城子.
- For ten years the living and death are both boundless./ Don't need to think intentionally,/ which is hard to forget./With your grave thousands miles away,/ where can I confide my loneliness?/ Even if we met, could you recognize me,/ dust all over my face/ temples have looked like frost?/
- Last night in dream I returned hometown./ By the window,/ you were combing your hair./ We looked at each other silently,/ with only endless tears./ There's a place which every year will be my misery,/ in moonlight,/ the cemetery hill with short pines./
- ——Su Shi, 蘇軾,《江城子·十年生死兩茫茫》
In the title of this cí, "Riverside City" is the name of cípái. Su Shi got married when he was 19, his wife 16. His wife died when she was only 27. Because of his government duties, Su Shi had moved to many different places in China, all far away from his hometown. One night in early 1075, about 10 years after her death, Su Shi dreamed of his wife, then composed this famous cí.
Famous cí poets
- Wen Tingyun (812–870)
- Wei Zhuang (836–910)
- Li Cunxu (885–926)
- Gu Xiong (fl. 928)
- Lu Qianyi (fl. 931)
- Yan Xuan (fl. 932)
- Mao Xizhen (fl. 947)
- Xue Zhaoyun (10th century)
- Sun Guangxian (d. 968)
- Li Yu (937–978)
- Liu Yong (987–1053)
- Ouyang Xiu (1007–1072)
- Su Shi (1037–1101)
- Song Ci (1186-1249)
- Huang Tingjian (1045–1105)
- Qin Guan (1049–1100)
- Zhou Bangyan (1056–1121)
- Li Qingzhao (1081–1149?)
- Lu You (1125–1209)
- Xin Qiji (1140–1207)
- Jiang Kui (1155–1221)
- Wang Yisun (1240?–1290?)
- Gao Bing (1350–1423)
- Qian Qianyi (1582–1664)
- Wu Weiye (1609–1671)
- Gong Dingzi (1615–1673)
- Chen Weisong (陈维崧 1626–1682)
- Zhu Yizun (1629–1709)
- Nalan Xingde (1655–1685)
- Mao Zedong (1893–1976)
- Kang-i Sun Chang. The evolution of Chinese tz'u poetry from late T'ang to Northern Sung.Princeton, New Jersey: Princeton University Press, 1980.
- Davis, A. R. (Albert Richard), Editor and Introduction,(1970), The Penguin Book of Chinese Verse. (Baltimore: Penguin Books).
- Frankel, Hans H. (1978). The Flowering Plum and the Palace Lady. (New Haven and London: Yale University Press) ISBN 0-300-02242-5
- Marsha Wagner, The lotus boat: origins of Chinese tz'u poetry in T'ang popular culture (New York: Columbia University Press, 1984.
- Zhang, Hongsheng (2002). "Gong Dingzi and the Courtesan Gu Mei: Their Romance and the Revival of the Song Lyric in the Ming-Qing Transition", in Hsiang Lectures on Chinese Poetry, Volume 2, Grace S. Fong, editor. (Montreal: Center for East Asian Research, McGill University).
- Frankel, 216
- Davis, lxvii
- Zhang, 76-80
- "Chinese Pronunciation - Tones". chinesepod.com. Retrieved 2018-11-20.
- "词牌", 维基百科，自由的百科全书 (in Chinese), 2018-03-08, retrieved 2018-11-20
- "格律", 维基百科，自由的百科全书 (in Chinese), 2013-08-07, retrieved 2018-11-20
- "江城子 (苏轼) - 维基文库，自由的图书馆". zh.wikisource.org (in Chinese). Retrieved 2018-11-20.