Poetry gives you permission to say any kind of language, using any kind of grammar.
Poems come in a variety of shapes. Although the best poems always have their own unique qualities, many of them also conform to traditional patterns. Frequently the form of a poem — its overall structure or shape — follows an already established design. A poem that can be categorized by the patterns of its lines, meter, rhymes, and stanzas is considered a fixed form because it follows a prescribed model such as a sonnet. However, poems written in a fixed form do not always fit models precisely; writers sometimes work variations on traditional forms to create innovative effects.
Not all poets are content with variations on traditional forms. Some prefer to create their own structures and shapes. Poems that do not conform to established patterns of meter, rhyme, and stanza are called free verse or open form poetry. (See Chapter 25 for further discussion of open forms.) This kind of poetry creates its own ordering principles through the careful arrangement of words and phrases in line lengths that embody rhythms appropriate to the meaning. Modern and contemporary poets in particular have learned to use the blank space on the page as a significant functional element (for a vivid example, see E. E. Cummings’s “l(a”). Good poetry of this kind is structured in ways that can be as demanding, interesting, and satisfying as fixed forms. Open and fixed forms represent different poetic styles, but they are identical in the sense that both use language in concentrated ways to convey meanings, experiences, emotions, and effects.