Harmony

Tonic, subdominant and dominant — the three main chord roles in a key. Understanding functions helps build logical progressions.

A secondary dominant temporarily acts as a dominant to any degree other than the tonic. It is one of the most powerful tools for enriching harmony.

Borrowed chords (modal interchange) — chords from the parallel key that add unexpected color to the harmony.

Tritone substitution replaces a dominant seventh with a chord a tritone away. A key tool in jazz harmony.

Voice leading is the movement of individual voices during chord changes. Good voice leading minimizes jumps and creates smooth melodic lines.

Modal interchange lets you borrow chords from parallel modes, enriching major or minor harmony.

Chord substitution enriches harmony by replacing one chord with another that shares a similar function but has a different sound.

Reharmonization replaces a melody's harmony with new chords. The melody stays the same but sounds in a new harmonic context.