What is an artsong?

An artsong is a song that sets words to music using compositional techniques that stem from the classical tradition. The text can come from a variety of sources: poems, letters, a libretto, a speech, etc. 

The majority of artsongs have been scored for voice with piano. However, more than one voice can be used; any instrument(s) can accompany the voice; and if desired, the voice(s) can sing without accompaniment.

My own preference is to set poetry to music.