A song is a musical composition. Songs contain vocal parts that are performed with the human voice and generally feature words (lyrics), commonly accompanied by other musical instruments (exceptions would be a cappella and scat songs). The words of songs are typically of a poetic, rhyming nature, although they may be religious verses or free prose.

Songs are typically for a solo singer, though there may also be a duet, trio, or more voices (works with more than one voice to a part, however, are considered choral). Songs can be broadly divided into many different forms, depending on the criteria used. One division is between "art songs", "popular music songs", and "folk songs". Other common methods of classification are by purpose (sacred vs secular), by style (dance, ballad, Lieder, etc), or by time of origin (Renaissance, Contemporary, etc).

Colloquially, song is sometimes used as slang to refer to any music composition, even those without vocals. In European classical music, jazz, brass band, popular music, and many other musical styles however, this usage is considered incorrect. "Song" should only be used to describe a composition for the human vocals. In music styles that are predominantly vocal-based, a composition without vocals is often called an instrumental. A musical piece that may be either with or without vocals can be called a melody, a tune, or a composition.

[edit] Art songs
Art songs are songs created for performance in their own right, or for the purposes of a European upper class, usually with piano accompaniment, although they can also have other types of accompaniment such as an orchestra or string quartet, and are always notated. Generally they have an identified author(s) and require voice training for acceptable performances. The German-speaking communities to refer to the serious art song, whereas in German-speaking communities the word "Kunstlied" (plural: "Kunstlieder") is used to distinguish art song from folk song ("Volkslied"). The lyrics are often written by a lyricist and the music separately by a composer. Art songs may be more formally complicated than popular or folk songs, though many early Lieder by the likes of Franz Schubert are in simple strophic form. They are often important to national identity. Art songs feature in many European cultures, including but not limited to: Russian (romansy), Dutch (lied), Italian (canzoni), French (mélodies), Scandinavian (sånger), Spanish (canciones). There are also highly regarded British and American art songs in the English language. Cultures outside of Europe may have what they consider to be a classical music tradition, such as India, and thus feature art songs. good and very usefull. The accompaniment of pieces of this period is considered as an important part of the composition. The art song of this period is often a duet in which the vocalist and accompanist share in interpretive importance. The pieces were most often written to be performed in a home setting although today the works enjoy popularity as concert pieces. The emergence of poetry during this era was much of what inspired the creation of these pieces by Brahms, Schumann, Schubert and other period composers. These composers set poems in their native language. Many works were inspired by Johann Wolfgang von Goethe and Heinrich Heine. Another method would be to write new music for each stanza to create a unique form, this was through-composed form known in German as durchkomponiert. A combination of both of these techniques in a single setting was called a modified strophic form. Often romantic art songs sharing similar elements were grouped as a song cycle. (Kamien, 217–18) like garrison