ii–V–I

The backbone

The ii–V–I is the most important progression in western harmony. In C, that's Dm7, G7, Cmaj7 — tension, more tension, release.

Why it works

ii     Dm7 — sets up, minor, stable
V      G7 — dominant, wants to resolve
I      Cmaj7 — home, the release

Where you'll hear it

Jazz standards, but also half of pop and almost every Christmas song. It's the pull of a chord wanting to go home, twice in a row.