Poetry doesn’t necessarily have to conform to limits or formats of any kind, although it can. Poems can be as long as books, such as “Paradise Lost,” or two lines long, like Ezra Pound’s “In a Station of the Metro.” They don’t have to rhyme or follow any kind of rhythm structure or scheme, or they can be rigidly formulaic. Unlike other types of literature, poetry is limitless in its possibilities, not only in terms of content but also in form. Poetry is probably the most flexible literary genre.
You can usually identify a poem first by how it looks. As simplistic as it sounds, the lines do not always cross the page, whereas this is almost always true for prose. A poem might contain only one word on a line, or leave a line blank altogether. The text of a poem can even take the shape of an image discussed in the poem. In a concrete poem, the writer makes the text of the poem in the shape of the poem’s topic. For example, George Herbert’s poem “Easter Wings” is shaped like a pair of wings.
Although a novelist may sometimes write in a flowing, soothing-sounding poetic style, a poet frequently considers the sound of every syllable in her writing. Poets often use sound devices, such as rhyme, rhythm, alliteration, onomatopoeia or assonance. This involves using words that have similar endings, begin with the same consonants or repeat the same vowel sounds. These techniques influence how a poem sounds when read aloud. They help establish the mood and tone of a poem, thereby contributing to the overall experience of a poem.
Poems can certainly contain a plot line with rising action that builds to a climax. They also may include characters, as in “The Rime of the Ancient Mariner” by Samuel Taylor Coleridge, but this is not a defining characteristic of poetry. A poem can cover as much or as little material as possible. It can simply capture a single image or sensation, such as in Haiku poetry, or it can read like a soliloquy of someone’s private thoughts. It could be a lament or a celebration, or a memory, but it doesn’t have to contain a story.
Novels tend to be easy to read. You can sit down and become absorbed by a book for an hour or more. Poems, on the other hand, typically require slow and careful study to glean their full meaning. The lines of a poem tend to be more complex, more “packed with meaning,” than lines of text in other types of literature. Because many poems throw grammar to the wind, this lack of familiar structure can make it even more difficult to understand. Punctuation, capitalization and full sentences help guide readers along text, so the absence of them can have a disorienting effect.