A poem is a piece of writing that expresses a writers feelings or the feelings of a persona, usually using some kind of rhyme scheme or metrical pattern. Traditionally, poems were defined by their use of rhyme schemes and metrical patterns, but contemporary poets often choose to exclude rhyme and rhythm from their verse, opting to write in free verse. While today most poems are written without a set form, some formal possibilities include free verse, rhymed poems, sonnets, haikus, and ballads. Poetry is a form of literary art that uses aesthetic and rhythmic qualities of language, such as phonoaesthetics and sound symbolism, to evoke a concentrated imaginative awareness of experience or a specific emotional response through language. Poetry is difficult to define, and there are many different opinions on what makes something a poem. Some people believe that a poem is a home for deep feelings, stunning images, beautiful lyricism, tender reflections, and/or biting wit, while others believe that poetry is when an emotion has found its thought and the thought has found words. Ultimately, a poem is a creative expression that can take many forms and serve many purposes.