It is impossible to trace poetry to a definite beginning, as it is likely as old as the human spoken word. The oldest recorded poetry is contained in the cuneiform tablets of ancient Mesopotamia circa 3,000 B.C. Classical Chinese poetry has its roots in the form of song lyrics dating to 1,000 B.C. Poetry appears in all the major religious canons, such as the Sanskrit Vedas, the Hebrew Tanakh and the Greek Bible. In the West, poetry has evolved from such ancient Greek masterpieces as Homer's "Odyssey" and "Iliad" circa 900 B.C., on into the Romantic poetry of Western Europe, and through the modern and postmodern periods to the present.
Poetry was born of a basic human desire to communicate not just the meaning of words, but also the sense or feel of them. Writers use poetry to evoke a mood in the reader or listener, so that the experience can occur on multiple levels of the human psyche. In rhetoric, elements of poetry are used to help the audience comprehend the message more clearly. In music, poetry is often used to evoke laughter, tears and other human emotional responses.
Poetry takes on many forms. One common type of poetry is rhyming couplets, in which each successive pair of lines are approximately the same length and rhyme with one another. In free-form poetry, rhyme and meter are loose, allowing for complex rhythms and greater contextual freedom. Poems can be long or short. "The Rime of the Ancient Mariner" by Samuel Taylor Coleridge is a well known long-form poem that tells a story. Haiku, a short form of poetry, strives to evoke a moment or mood in just three short lines. With the advent of post-modernism (and even post-post-modernism), the rules have been successively cast out, reclaimed, taken apart and reassembled countless times. As a result, the "types" of poetry will never be completely standardized.
Poetry contains the features of both literature and music. One of the most recognizable elements of poetry is metaphor, a literary technique used to compare one thing to another ("A" is like "B, or "X" is "Y"). Imagery, another basic literary element of poetry, is often used to paint a picture in the mind of the reader or listener. To evoke a sense of authenticity some poets use vernacular language, as in the language of hip hop. On the musical side of poetry, there is rhyme, rhythm, meter, tone, pacing and other aural elements. Whether written or spoken, the musical features of poetry appeal to the human ear and thus play a crucial role in establishing mood.
Not all poetry has to rhyme. Yes, rhyme often helps a poem to succeed, as the human ear enjoys hearing things in pairs. But just as with symphonic music of the modern period, poetry can be musical without rhyming. On the other hand, free-form poetry does not mean "anything goes." All poetry, by definition, must contain musical elements, however subtle, and some intentionality with regard to the language. It can be difficult to distinguish between a free-form poem and a string of random words, but that is part of the attraction of poetry: aesthetic quality is in the ear of the beholder.