Chord Progressions

What this section teaches

Songs repeat each other on purpose. A handful of chord patterns — the 12-bar blues, the ii–V–I, the four-chord "Axis," the doo-wop turnaround — account for a staggering share of popular music, and they persist because each one solves the same problem beautifully: how to leave home, build tension, and return. This library documents the famous patterns in Roman numerals, the notation that names chords by their role in the key instead of their letter. I–V–vi–IV is the same progression in C or in Eb; the numerals are what let you steal it, transpose it, and recognize it on one hearing.

How to use these pages

Each progression's page explains why the pattern works, names famous songs built on it, tags the moods it carries, and writes the chords out in every key. Learn one pattern at a time: read its logic, listen to two of its songs, then play or sing it in a couple of keys until the shape — not the letter names — is what you remember. Writing a song, start from the mood: the library is indexed by feel as well as by name, and swapping one chord of a famous pattern is the oldest songwriting move there is.

Where to go next

The numerals come from keys; the tension-and-release logic is unpacked in functional harmony and cadences; and the transposer will move any progression to any key instantly.