Cí (pronounced [tš]; Chinese: ?) 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 (/, "lines of irregular lengths") and Shiyu (/, "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 (). 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, and several ci often shared the same title had had little or nothing to do with the topics of those poems, which rather referred to 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; although in the case of the cí form some of its fixed-rhythm patterns have an origin in Central Asia. The form was further developed in the Tang Dynasty. Although the contributions of Li Bai (also known as Li Po, 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.
Two main categories of cí employed in Song Dynasty were xi?olìng (the original form since Pre-Song) and màncí (starting after Liu Yong), depending on the song being either short and in fast tempo or long and in slow tempo. Later in Ming Dynasty and Qing Dynasties, the cí, or rather the cípái, are classified for the number of characters it dictates. It's called xi?olìng if it's no more than 58 characters, zh?ngdiào for 59-90, and chángdiào for over 90. If the ci appears in one stanza, it's called d?ndiào , mostly xi?olìng written in Pre-Song era. The largest majority is shu?ngdiào with two stanzas or qüè ? in identical or nearly identical patterns. There also are rare cases of s?ndié and sìdié , for three and four qüè, respectively. In terms of style, cí can also be classified as either w?nyu? (grace) or háofàng (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 popflock.com resource 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" (? píng), "rising" (? sh?ng), "departing" (? qù), and "entering" (? rù) tones." The level is classified in ?,the rising, departing and entering are classified in ?. So, in any Cipai, the formation of Ci, each Chinese character in Ci will be required in detailed tones with ? or ?.
Cipai, is also called as Cige, Cidiao, which is the name of various formation 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, we choose a Ci ().
The tones requirement of each characters in this Cipai is following:
The following content is a cí poetry of .
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.