Chord Progressions

A chord progression is a sequence of chords that creates harmonic motion. The choice of progression shapes the emotional feel of music more than almost anything else — tempo, instrumentation, and arrangement all dress the song, but the chord changes are the skeleton. Certain progressions have become so common they're essentially part of a shared musical vocabulary.

The Diatonic Chords

Build a chord on each note of the major scale using only the notes of that scale. In C major:

Numeral	Chord (C major)	Quality	Function
I	Cmaj7	Major 7th	Tonic — home, resolved
ii	Dm7	Minor 7th	Pre-dominant — movement away from tonic
iii	Em7	Minor 7th	Tonic substitute — shares notes with I
IV	Fmaj7	Major 7th	Subdominant — classic contrast
V	G7	Dominant 7th	Dominant — strongest pull to I
vi	Am7	Minor 7th	Relative minor — tonic-like quality
vii°	Bm7♭5	Half-diminished	Dominant function, rarely used as is

Roman numerals uppercase for major chords, lowercase for minor. The dominant (V) contains the tritone between its 3rd and 7th (B and F in G7) — the strongest possible pull toward the tonic.

ii–V–I: The Jazz Engine

The most important three-chord progression in jazz. Nearly every standard contains ii-V-I sequences — recognising and knowing how to play through them is the foundation of jazz vocabulary:

In C major: Dm7 → G7 → Cmaj7
In F major: Gm7 → C7 → Fmaj7
In B♭ major: Cm7 → F7 → B♭maj7
In A major: Bm7 → E7 → Amaj7
In Eb major: Fm7 → B♭7 → E♭maj7

Chord in ii-V-I	Roman numeral	Function	Common scales
Dm7 (in C)	ii	Pre-dominant — sets up tension	Dorian, scales of parent major key
G7 (in C)	V	Dominant — maximum tension	Mixolydian, bebop dominant, altered
Cmaj7 (in C)	I	Tonic — resolution	Ionian, Lydian, major bebop

I–IV–V: The Vernacular

The backbone of blues, rock, country, and folk.
Three chords → hundreds of songs.

In C: C — F — G   (Cmaj7, Fmaj7, G7 in jazz; C, F, G in rock)
In G: G — C — D
In A: A — D — E
In E: E — A — B

12-bar blues in A (I7, IV7, V7 = dominant sevenths throughout):
A7 | A7 | A7 | A7 |
D7 | D7 | A7 | A7 |
E7 | D7 | A7 | E7 |

I–V–vi–IV: The Pop Rotation

In C: C — G — Am — F
In G: G — D — Em — C
In D: D — A — Bm — G
In E: E — B — C#m — A

Famously demonstrated to underlie dozens of hit songs:
"No Woman No Cry," "Let Her Go," "Let It Be," "With or Without You,"
"Someone Like You," "Poker Face" — same four chords, different arrangements.

I–IV–vi–V and Variations

The same four chords rearranged create different emotional flavours:

I–V–vi–IV (standard pop): resolved → motion → darker → lift
vi–IV–I–V (start on minor): darker start, more introspective
IV–I–V–vi: starts on the lift chord
vi–IV–V–I: traditional resolution at the end

Common Progressions Reference

Name	Numerals	Example (C major)	Genre
I–IV–V	I IV V	C F G	Blues, rock, country, folk
ii–V–I	ii V I	Dm7 G7 Cmaj7	Jazz (everywhere)
Pop 4-chord	I V vi IV	C G Am F	Pop, rock, worship music
50s progression	I vi IV V	C Am F G	Doo-wop, 1950s pop
Minor i–♭VII–♭VI–♭VII	i ♭VII ♭VI ♭VII	Am G F G	Rock, pop-rock
Andalusian cadence	i ♭VII ♭VI V	Am G F E7	Flamenco, Spanish guitar
Pachelbel Canon	I V vi iii IV I IV V	C G Am Em F C F G	Classical, pop (widely quoted)
Rhythm changes (A section)	I VI ii V	B♭ G7 Cm7 F7	Jazz (Gershwin era standards)
Minor ii°–V–i	ii° V7 i	Bm7♭5 E7 Am	Jazz minor key, classical cadences

Secondary Dominants

Any diatonic chord can be preceded by its own dominant seventh chord — a chord borrowed from outside the key that creates a temporary tonicisation:

V/V (five of five) → V → I
In C: D7 → G7 → Cmaj7
  D7 is the dominant of G — the D7 makes G feel like a temporary tonic.

V/ii → ii:  A7 → Dm7      (A7 is the dominant of Dm)
V/IV → IV:  C7 → Fmaj7    (C7 is the dominant of F)
V/vi → vi:  E7 → Am7      (E7 is the dominant of Am)

Modal Interchange (Borrowing)

Borrow chords from the parallel minor to add dark colour in a major key context:

In C major, borrowed from C minor:
  iv (Fm)   — minor subdominant. Dark, poignant. "Let It Be" uses Fm before C.
  ♭VII (B♭) — borrowed major chord. Rock/modal feel.
  ♭VI (A♭)  — dramatic. "In My Life" uses ♭VI-♭VII-I.
  ♭III (E♭) — borrowed, gives a flat-key lift.

References

Levine — The Jazz Theory Book
Rawlins & Bahha — Jazzology
Hooktheory — chord progressions in real songs ↗