(1) Metric poem: a poem written according to a certain format and rules. It has strict rules on the number of lines, the number of words (or syllables), the tone and rhyme, the antithesis of words and the arrangement of sentence patterns. Such as the metrical poems, quatrains and songs in China's ancient poems and the European sonnets.
② Free verse: a newly developed poetic style in modern Europe and America. It is not limited by metrical rules, has no fixed format, pays attention to natural and internal rhythm, and uses rhymes roughly similar or without rhymes. The number of words, lines, sentence patterns and tones are relatively free, and the language is relatively popular. Whitman, an American poet (1819-1892), is the founder of European and American free verse, and Leaves of Grass is his main collection of poems. This poetic style has also become popular in China since the May 4th Movement.