What Is Harmony?

Play a single C. There is no harmony yet, only one note. Add the G seven semitones above it and the two notes blend into one sound. Add E between them and you have C major: three notes, heard as a single chord.

That stacked sound, several notes at one moment, is harmony in its simplest form. What Is a Chord? builds it one note at a time.

The word also covers what happens over time. Play the four chords in the listening block: C, F, G, C. Each one is a harmony of its own, and so is the change from one to the next. When musicians say a song has interesting harmony, they usually mean the way its chords move.

Most of them come from a scale. Take the seven notes of C major, C D E F G A B, and stack every other note starting from each one. From C you get C, E, G. From D you get D, F, A. Keep going and you end up with seven chords:

C, Dm, Em, F, G, Am, Bdim

Every note in all seven chords comes from the same seven-note scale. C, F and G in the listening block are three of them, and they are the three major chords of the key.

The same method works in every key and always gives the same row of types: major, minor, minor, major, major, minor, diminished. Diatonic Chords lays out that row for all twelve.

Play the progression again and stop it on the G. It hangs there, waiting. Let it continue to C and it lands.

Look at the notes. A G major chord is G, B and D, and the B sits one semitone below C. Moving from G to C takes that B up one step to C, and a note resolving by a single semitone is one of the strongest pulls in harmony.

Musicians call C the tonic, the chord that feels like home, and G the dominant, the chord that most wants to go there. Much of harmony comes down to this: which chords feel settled, and which ones want to move on. Harmonic Function gives every chord in the key its role, and Cadences covers the four common ways a phrase ends.

Press B and C together. The two notes are one semitone apart, and they rub. Now press C and G, seven semitones apart, and they blend.

That difference has names: notes that blend are consonant, notes that rub are dissonant. Consonance and Dissonance explains where it comes from.

Add F to the G chord and you get G7: G, B, D, F. The B and the F are six semitones apart, an interval that rubs hard. Move on to C and the B rises to C while the F falls to E, and the rub is gone. That is why G7 to C sounds even more final than G to C. The tension is written into the chord, and the next chord releases it.

A melody is one note at a time, the line you would sing. The harmony is what sounds underneath and around it. In the listening block there is no melody at all, only chords.

When a melody and its chords work together, the melody notes that fall on strong beats are usually notes of the chord playing underneath. Melody and Harmony shows how to check that note by note, and Voice Leading covers how each note of one chord moves to the next.