Chord Progressions

A chord progression is a sequence of chords played one after another in time. One chord is a static sound. A progression is a journey: it leaves somewhere, goes somewhere, and (usually) comes back.

The simplest journey in music starts at home, steps away, builds a little tension, and returns. In C major that is C → F → G → C. Play each chord in order and notice how the last C feels different from the first one: it feels earned.

Musicians name the chords of a key with Roman numerals, one for each scale degree the chord is built on. The chord built on degree 1 is I, on degree 4 is IV, on degree 5 is V, and so on.

• Uppercase = major chord: I IV V C F G
• Lowercase = minor chord: ii iii vi Dm Em Am
• Lowercase with ° = diminished chord: vii° Bdim

Why not just say "C, F, G"? Because numerals are relative, exactly like scale degrees. I → IV → V → I describes the same musical motion in every key. In C major it is C F G C. In G major it is G C D G. The letters change. The numerals, and the feeling, never do.

Every major key contains exactly seven chords made only from the notes of its scale: the diatonic chords. Here is the build rule: stand on any scale degree and stack 1 3 5 using only scale notes, meaning the degree itself, the note two scale steps above it, and the note two scale steps above that.

The qualities are not random. Each chord's third and fifth are simply the intervals the scale hands you from that degree. From 1, 4 and 5 the scale gives a major third and a perfect fifth, so those chords are major. From 2, 3 and 6 it gives a minor third and a perfect fifth, so those are minor. From 7 it gives a minor third and a diminished fifth, so vii° is diminished. The pattern major, minor, minor, major, major, minor, diminished comes out the same in every major key. Learn it once and you know the chords of all twelve keys.

Chords have jobs, and the first job is tonic: the feeling of home, rest, and resolution. The chord I is the tonic itself, but two other chords share so many notes with it that they can stand in for home with a different shade.

Play I, then vi, then I again. The vi does not feel like a departure so much as the same room with the lights dimmed. Songs use vi to make a chorus turn wistful without leaving home.

The second job is subdominant: stepping away from home without creating real tension. Subdominant chords open the door. They say "something is about to happen", and they contain degree 4, the note that most wants to fall back to 3.

IV and ii share two notes (F and A), which is why they are interchangeable in so many songs. IV is the everyday choice in pop and folk. ii is the smoother, jazzier one because its root D sits a fifth above G, the chord it most often leads to.

The third job is dominant: building tension that wants to resolve to the tonic. Dominant chords contain degree 7, the leading tone, which sits a minor second below 1 (a single semitone) and pulls toward it like a magnet.

Both chords hold the leading tone B, and vii° adds degree 4 (F) on top, so it contains both tendency tones at once: B wants to rise to C, F wants to fall to E. That is why it cannot sit still. V → I is the single most important move in Western harmony. Play it and hear the release.

Now the three functions become progressions. I-IV-V-I is the complete sentence: tonic, subdominant, dominant, tonic. It is the engine of blues, folk, country and early rock and roll. Every function appears once, in order.

Swap the middle around and add vi, and you get I-V-vi-IV, probably the most-used four-chord loop of the last fifty years. It starts confidently at home, jumps straight to the tension of V, softens into the shadow of vi, and rests on the open IV before looping back to I.

C, G, Am and F can be arranged in a loop and started from any of the four chords. And where you start changes the whole feeling. The loop repeats, so the ear treats whichever chord comes first (and lands on the downbeat) as the emotional centre.

vi-IV-I-V begins in the minor shadow and ends on V, so every repeat feels like a question left hanging. That is its yearning quality. "Zombie" (The Cranberries) rides this loop in G major (Em C G D). I-vi-IV-V also starts at home but passes through vi immediately, then walks IV → V back to the top: the sound of "Stand By Me" (Ben E. King), in A major (A F#m D E).

ii-V-I is the three-chord sentence at the heart of jazz and much classical music: subdominant → dominant → tonic, using ii instead of IV for the first step. Each root falls a fifth (D → G → C), and root motion by falling fifths is the strongest pull in harmony.

Jazz almost always plays these as seventh chords: a fourth note stacked on top of each triad, still using only scale notes. Same functions, richer colour, and even smoother connections between chords.

Read each formula as intervals above the chord's own root. b7 is a minor seventh: C above D, F above G. 7 is a major seventh: B above C. b3 is a minor third: F above D. That is the whole difference between the three seventh chords.

Because numerals are relative, a progression can be transposed, moved to another key, by rebuilding each numeral on the new scale. Let's move I-V-vi-IV from C major to G major and to F major.

Notice that the V of G major needs the F# from the G major scale (D F# A), and the IV of F major needs the Bb (Bb D F). The accidentals of the key carry straight into its chords. Play the three versions in a row: three different pitch levels, one identical feeling.

Voice leading is how the individual notes inside one chord travel to the notes of the next. The same progression can sound jumpy or seamless depending only on which notes move and how far.

• Keep common tones: a note that belongs to both chords stays exactly where it is.
• Move the rest by the smallest distance: a second (a minor or major second) whenever possible.
• Avoid leaping every voice to a new root-position shape.

Example: I → vi, C to Am. Both chords contain C and E, so those stay. Only G moves, up a major second to A. Result: C3 E3 G3 → C3 E3 A3. Compare it with jumping to a root-position A3 C4 E4, where every voice leaps.

The same idea gives a smooth I → V: keep the shared G, move C down a minor second to B and E down a major second to D: C3 E3 G3 → B2 D3 G3. Good voice leading is why a piano or a choir can play the same four chords for three minutes and never sound clumsy.

Step back and the whole chapter fits in one sentence: a chord progression is functions in motion. Tonic, subdominant and dominant take turns, with the leading tone pulling everything back to I.

Look at the strongest root motions we met: IV → I (F to C), V → I (G to C), ii → V (D to G). Every one of them is a root falling by a fifth. ii-V-I is two falling fifths in a row. That is not a coincidence. It is the pattern the next chapter is about.