Harmony
Chords mean nothing alone — harmony is what happens between them. Eight guides explain the moves; the reference sections supply the material.
The guides
Read them in order for a course, or jump to the move a song just played on you. Every musical example in these guides is derived from the same tested theory data that powers the reference sections — and each guide links back to the chords, keys, and progressions it explains.
Functional harmony
The three jobs every chord can hold — and why hearing chords as jobs, not letters, is the single biggest upgrade to how you understand songs.
Start hereCadences
The four standard phrase endings — full stop, soft landing, open question, and surprise — and how to hear each one coming.
Phrase endingsVoice leading
Why some chord changes sound like one thing flowing into the next: common tones, small steps, and the notes that insist on moving.
The connective tissueBorrowed chords
The minor-key chords a major key loves to steal — iv, bVI, bVII — and the bittersweet shading they bring with them.
Modal interchangeSecondary dominants
Dominants aimed at chords other than the tonic: how one borrowed leading tone makes the next chord feel inevitable.
Aimed tensionThe ii–V–I
Prepare, tense, resolve: what actually happens inside Dm7–G7–Cmaj7, and why the same three-chord engine drives so many songs.
The jazz engineChord substitution basics
Reharmonize without breaking the song: relative swaps, added-color swaps, and the famous tritone substitution, all from shared notes.
Same job, new colorHow keys relate
Relative, parallel, and neighboring keys — the map of key relationships, and the pivot-chord move songs use to travel it.
Modulation primerThe reference behind the guides
Chord construction
Before chords can function, they have to be built — 62 qualities on any root, formula by formula.
The materialKeys & diatonic chords
The seven chords every key owns, with the Roman numerals harmony analysis is written in.
The contextProgressions
Function in action: the named patterns that move from tension to resolution, in every key.
The motionCircle of fifths
The map of key relationships that makes borrowed chords and modulation legible.
The map