What Is a Chord Progression? The Story of Leaving Home and Coming Back

In Part 3 we saw how a single chord makes a "color." But chords show their real power not standing alone — they come alive moving in a line. If one chord is a still photo, a chord progression — chords set in order — is a story. This post follows why and how chords move to create feeling: the journey of leaving home and coming back.

The chord family born from one scale

First, a question: can you just throw any chords into a song? Usually not. Most songs are built from chords born of a single scale. Stack thirds (as in Part 3) on each note of the C major scale (do-re-mi-fa-sol-la-ti) and you get seven chords: C, Dm, Em, F, G, Am and Bdim.

The neat part is that each position has a fixed brightness. The 1st, 4th and 5th are major; the 2nd, 3rd and 6th are minor; the 7th is diminished. That's why musicians often name chords with Roman numerals instead — I, ii, iii, IV, V, vi, vii°. That way the relationships stay visible no matter what key you move to. These seven are the chord family of a song.

Three roles — home, leaving, tension

Each of the seven chords has a job, and three of them are key. I (the tonic) is home — the most stable chord; end here and it feels like you've arrived. IV (the subdominant) is leaving — the sense of stepping out the door and opening up a little. V (the dominant) is tension — the chord that itches to rush back home.

Why does V pull so hard toward home (I)? Hidden inside V are the note a semitone below the tonic (the leading tone) and the restless tritone we met in Part 2. When that tautness releases onto I, you feel the pleasure of "ah, resolved." Leaving home (IV), building tension (V) and returning (I) — those three beats are the basic grammar of Western music.

The progressions that rule the world

String those roles together and you get progressions you hear everywhere. I-IV-V, home-leave- tension in a row, is the skeleton of countless songs from nursery rhymes to rock and roll. Lay those three chords across twelve bars and you get the 12-bar blues, practically the shared mother tongue of blues, rock and jazz. Lock this skeleton into your ear first.

Cadences — the punctuation of music

Just as speech has periods and commas, a progression has ways of ending a phrase — cadences. V-I is the perfect (authentic) cadence, a clean full stop. A phrase that halts on V is a half cadence, a comma that promises more. IV-I is the plagal cadence, the gentle close you hear in the "Amen" at the end of a hymn. And when V veers off to some chord other than home, it's a deceptive cadence — the "wait, that's not the end?" twist. Try to hear where a progression comes to rest.

Hear it — dozens of songs from just four chords

Here's the most vivid proof of a progression's power. I-V-vi-IV, the so-called "four pop chords," is the shared backbone of hundreds of hits over the past few decades. Just four chords cycling round, yet each song sounds completely different — the video below proves the magic delightfully.

That was the four-step tour of harmony basics: Part 1 on where notes come from, Part 2 on the distance between two notes, Part 3 on the color three notes make, and this part on the story those colors tell as they move. From here, tools like seventh chords, tensions and key changes wait to enrich the palette. But master just today's I-IV-V and cadences, and you'll slowly start to hear why your favorite songs move the way they do.