Chord Progression

A chord progression is a sequence of chords played one after another in a musical way. Almost every song is built on one, and the progression is what takes the listener on a journey of tension and release. Because the chords are diatonic to a key, progressions are written with Roman numerals - I, IV, V and so on - so the same pattern can be talked about in any key.

Tension and resolution

Progressions move between three roles. The tonic is the centre of gravity, the chord everything wants to resolve to. Subdominant chords move away from the tonic. Dominant chords are the most tense and pull hardest back home. The smallest unit of all this is a cadence: a move from a non-tonic chord to the tonic. The strongest is the perfect cadence, V to I, which underpins most Western music - the V chord is major precisely so its third leans up into the tonic.

Common progressions

A handful of patterns turn up again and again. I-IV-V is the bedrock of blues and rock; I-V-vi-IV powers countless pop songs; ii-V-I is the heartbeat of jazz. Pick a key, play any of these, and it works:

• I - IV - V
• I - V - vi - IV
• I - vi - IV - V
• ii - V - I

From there, progressions get extended and coloured - dominant sevenths add tension, and non-diatonic or "borrowed" chords step briefly outside the key for effect.