Poetry is an art form in which human language is used for its aesthetic qualities in addition to, or instead of, its notional and semantic content. It consists largely of oral or literary works in which language is used in a manner that is felt by its user and audience to differ from ordinary prose. It may use condensed or compressed form to convey emotion or ideas to the reader's or listener's mind or ear, it may also use devices such as assonance and repetition to achieve musical or incantatory effects. Poems frequently rely for their effect on imagery, word association, and the musical qualities of the language used. The interactive layering of all these effects to generate meaning is what marks poetry.