I–IV–V: I - IV - V progression in D major

I - IV - V

I–IV–V is a essential progression, shown here in D major (tonic D) with the degree sequence I - IV - V.

I-IV-V is the most essential progression in Western music: the three major diatonic chords of any key, underpinning blues, rock, folk, and countless traditional songs. These three degrees alone are enough to harmonize almost any melody in a major key.

See D major on the circle of fifths