Concrete poetry is a type of poetry in which the visual appearance of the words on the page is more important in conveying meaning than the verbal significance. The words are arranged in such a way as to depict their subject, and the graphic space plays a central role in both design and meaning. Concrete poetry is sometimes referred to as visual poetry, and it relates more to the visual than to the verbal arts, although there is a considerable overlap in the kind of product to which it refers. The term "concrete" was used after a group of artists exhibited their poetry alongside artists in the National Exhibition of Concrete Art, lasting from 1956 to 1957. Concrete poems are usually shaped or patterned in some way, and the way the words are arranged on the page depicts the subject matter. Concrete poetry can be written in free verse, meaning that the poems do not use a specific rhyme scheme or metrical pattern. Concrete poems are important because they use elements of literature as well as visual arts, and they depend on a certain visual in a way that most other types of poems do not.