The chord progression is the backbone of western civilization music. The harmony created by chords provide added expression to the melody. Jazz harmony consists of a set of typical progressions directly derived from the European classical music tradition.
The goal of the jazz accompanist is to compliment the soloist's ideas while outlining the given chord progression clearly. As we know, most jazz improvisations use and outline the harmony as a foundation for melodic ideas. (See jazz improvisation.)
This chord progressions series demonstrates the most common progressions found in jazz. They will help you hear and understand the recurrent harmonic traits found in traditional jazz repertoire.
Every story begins somewhere... and this one begins with (you guessed it!) The almighty major scale !
The major scale is made of seven notes from which we can harmonize seven corresponding chords. We qualify them as diatonic because they belong to the same tonality (or key). The diatonic chords in the key of C :
(triangle = major 7th ; dashed circle = minor7(b5) AKA half-diminished)
We will refer to the chords with roman numerals. C is I and Dm is II and so forth until VII. It's always relative to the key center.
Playing those chords in a cycle of ascending diatonic fourths (or descending fifths) we get the diatonic cycle as follows :
in roman numerals: IV - VII - III - VI - II - V - I - (I)
This is the source for many other segments of jazz harmony. I added the C dominant 7th in parenthesis because it's not part of the C major scale. It simply resolves naturally to F major (you know, artistic liberties!)
The diatonic cycle can be developed in many other basic jazz progressions. One example is the enclosed Dm7-G7 which is the infamous II-V found everywhere in jazz. Study the diatonic cycle carefully.