Traditionally, poems followed rigid guidelines concerning rhyme, rhythm and meter. Sonnets, for example, contain a certain number of syllables per line and rhyme every other line, among other features. Certain kinds of poems contain a given number of stanzas, or paragraphs. Contemporary poetry usually throws convention to the wind and ignores structural patterns. Also known as free verse, many poets prefer this approach to poetry writing because it offers greater artistic freedom.
Although most poets craft free verse poems today, many still rely on poetic devices to enhance the experience of their writing. Poetic devices include assonance, the repetition of vowel sounds (as in "big flip"); consonance, the repetition of consonants (as in "Which watch?"); and oxymoron, a seeming paradox (as in "bitter sweet"). These devices add texture to a poem, especially when read out loud.
Often people describe poetry as an expression of emotion, but a poet can write about any topic. Sonnets and odes are, by convention, emotional poems, but epics detail heroic deeds and battles, which may or may not include emotional digressions. Limericks convey humor, and haikus paint images with words.
Readers who look for a code to decipher a poem are missing the point. The purpose of a poem is to offer a pleasurable experience for the reader. Poetry is meant to be experienced and enjoyed. By nature, it encourages reflection, but poems are not required to convey a message or point. Like a painting on a wall, a poem offers something for the imagination to ponder and mull over. This is the defining feature of a poem.