Functional harmony is a broad topic, but it begins with a few essential principles. The most important idea is that dominant chords resolve to tonic chords. This motion forms the backbone of harmonic progression and informs how other chords behave.
- Secondary Dominant chords are an extension of the same principle while borrowing chords from other keys.
- Tri-tone subs are replacements for Dominant chords.
- Minor IV Chords introduce a change in color by borrowing from the parallel minor.
- Generally diminished chords are replacements for Dominant chords
These foundational elements account for the vast majority of functional harmonic movement. Beyond them lie the complexities of extended harmony, altered dominants, and modulation, which enrich the harmonic palette but rely on the same underlying principles.
