HARMONY

In this chapter, we shall define harmony. This will be an easy task since we have already learned almost everything that needs to be understood about harmony. 

Harmonic support

A melody itself can be considered as music. However, a melody alone sounds empty. It needs harmonic support. Harmonic support is given with chords. When we speak of a chord, we mean it in a wider sense, as any combination of notes that are close in time and imply a chord. That is, simultaneously sounding notes (block chords), notes in a sequence (like broken chord) or any combination of the two (see chapter Broken chords and chapter Implied chords, chord tones and nonchord tones, both from the Part I of the book).

In chapter Naming and annotating chords, we learned how to build chords. In other words, we learned how to choose notes that sound good when played together. Composers use this knowledge when searching for musically pleasing harmonic support. However, this knowledge is not enough. They must also learn harmony. 

Harmony and chord progressions

Harmony studies chords and sequences of chords that occur commonly in music and, as we shall see, it always relates them to the current key. When we speak of the current key, we mean the key in which the passage that contains the chords is written. Studying chords related to the current key helps composers learn to create harmonic support in which not only does each chord sounds good for itself but also sounds naturally belonging to the whole passage containing the chords. We shall start studying chords related to the current key in chapters Diatonic chords and Altered chords. 

Sequences of chords are called chord progressions. Studying chord progressions helps composers to learn to create harmonic support which contains sequences of chords that sound logical and aesthetically pleasing. Some typical and important chord progressions will be explained in chapter Chord progressions. 

First, we shall take some time to learn how to annotate harmony.