This is the name of a poetic style. In a broad sense, lüshi (律诗) is poetry which stresses the requirements for rhythmic rules and forms; in a narrow sense, lüshi refers to such poetry other than quatrains with five- or seven-character lines, including five-character eight-line rhythmic poetry, seven-character eight-line rhythmic poetry, and five- or seven-character rhythmic poetry with ten or more lines. In ancient times, there were no strict regulations in regard to the rhythm of Chinese poetry. By the Southern Dynasties, however, the Yongming style, also known as the ”new poetry,” emerged, and began to demand the standardization of rhyme. In the early Tang Dynasty, based on the creation and exploration of some literati, poetic rules and forms gradually took shape, and rules-based poems were called contemporary or modern style poems, metrical poems or lüshi. Poems written before the establishment of poetic rules and forms or those created by later generations that did not follow the established rules and forms were called ancient style poems. The distinctive features of lüshi include the following: first, each line has the same number of characters, either five characters or seven characters. Second, the final characters of even sentences are rhyming with the level tone. Third, the poems with five- or seven-character lines each has eight lines, which can be broken down to four couplets, or pairs of related lines, namely, the first, second, third, and fourth pairs, and the second and third pairs must both be rhymed. Fourth, the characters used in the poem are arranged by level and oblique tones according to set rules. The characters in the same line must alternate between level and oblique tones. The characters of the lines in the same pair must match in level and oblique tones, and two related lines must be relative to each other. A lüshi poem with more than eight lines, whether it has five or seven characters per line, is just like adding rhymed and parallel pairs of lines between the first and last pairs. Orderly in form and harmony, and full of rhythm, lüshi is one of the most important styles of ancient Chinese poetry.

After the establishment of the Tang Dynasty, official schools were greatly revitalized. A great number of poems and articles were created, and literary talent emerged one after another. Moreover, poets like Shen Quanqi and Song Zhiwen delved deep into the art of poetry. Their poems are now called lüshi because their wording and rhythm are precise and appropriate, as well as euphonic. (Yuan Zhen: An Inscription with Preface to the Tomb of Du Fu, the Late Staff Member of the Ministry of Works of the Tang Dynasty)

Shen Quanqi and Song Zhiwen were the co-founders of lüshi in the Tang Dynasty. The poem cited here may not be particularly brilliant, but it is serene and proper, and the metrical patterns are orderly and appropriate. (Fang Hui: The Best Regulated Poems of the Tang and Song Dynasties)