The term "four-part harmony" refers to music written for four voices, or for some other musical medium—four musical instruments or a single keyboard instrument, for example—for which the various musical parts can give a different note for each chord of the music.Learn the fundamentals of four-part writing in this, the latest book in a series of books on music by an award-winning composer. A great way to begin learning the fundamentals of four-part harmony is to study four-part vocal writing. Even if you do not intend to write for voice, much of what you learn in four-part vocal writing can also be applied to instrumental music.