In its broadest sense, the
head of a piece of
music is its main
theme, particularly in
jazz, where the term takes on a more specific set of connotations. In other types of music, "head" may refer to the first or most prominent section of a song. The term may, though obtusely, be applied to
classical music, insofar as classical pieces generally bear similar thematic elements, but the preferred term in this instance is (main)
theme or
subject. The term "head" is most often used in jazz and may refer to the thematic
melody, an instance of it in a performance of the song, or a more abstract compilation of ideas as to what the song is. It may also, though uncommonly, refer to the first section of the melody, or the theme
riff in the melody.