Since it is a poem, it should be concise, rhythmic and rhyme at the end of the sentence. At the same time, we should have content and rich feelings. As for the number of lines, I don't care. In particular, refined words, rhythmic sounds and rhymes at the end of sentences are essential for poetry, otherwise what is written can only be called prose at most. "Sonnet" is actually a sentence used by some foreign poets to express the content of poetry. It is not a specific format of modern poetry. "Free Poetry" refers to modern poetry, which is relative to the fact that metrical poetry is subject to fixed rules and is not free.
Metric poems have requirements for the number of words in poems, while prose poems are generally small in length and few in words. According to the phonological rhythm and structural form of the language, it can be divided into metrical poems, free poems, prose poems and rhyming poems, and classified according to the phonological rhythm and structural form of the language of the work.