In jazz

Jazz

Jazz is a musical style that originated at the beginning of the 20th century in African American communities in the Southern United States. It was born out of a mix of African and European music traditions. From its early development until the present, jazz has incorporated music from 19th and 20th...

, a constant structure is a chord progression

Chord progression

A chord progression is a series of musical chords, or chord changes that "aims for a definite goal" of establishing a tonality founded on a key, root or tonic chord. In other words, the succession of root relationships...

 consisting of three or more chords

Chord (music)

A chord in music is any harmonic set of two–three or more notes that is heard as if sounding simultaneously. These need not actually be played together: arpeggios and broken chords may for many practical and theoretical purposes be understood as chords...

 of the same type or quality. Popularized by pianists Bill Evans

Bill Evans

William John Evans, known as Bill Evans was an American jazz pianist. His use of impressionist harmony, inventive interpretation of traditional jazz repertoire, and trademark rhythmically independent, "singing" melodic lines influenced a generation of pianists including: Chick Corea, Herbie...

 and Herbie Hancock

Herbie Hancock

Herbert Jeffrey "Herbie" Hancock is an American pianist, bandleader and composer. As part of Miles Davis's "second great quintet," Hancock helped to redefine the role of a jazz rhythm section and was one of the primary architects of the "post-bop" sound...

, the combination of functional

Diatonic function

In tonal music theory, a diatonic function is the specific, recognized role of each of the 7 notes and their chords in relation to the diatonic key...

 and non-functional chords provides cohesiveness while producing a free and shifting tonal center

Tonic (music)

In music, the tonic is the first scale degree of the diatonic scale and the tonal center or final resolution tone. The triad formed on the tonic note, the tonic chord, is thus the most significant chord...

.
For example, the progression Fmaj7-Amaj7-Dmaj7-Gmaj7-C13sus contains four major seventh chord

Major seventh chord

In music, a major seventh chord is any nondominant seventh chord where the "third" note is a major third above the root.Most typically, major seventh chord refers to where the "seventh" note is a major seventh above the root . This is more precisely known as the major/major seventh chord, and it...

s (and one thirteenth chord), none of which are diatonic

Diatonic and chromatic

Diatonic and chromatic are terms in music theory that are most often used to characterize scales, and are also applied to intervals, chords, notes, musical styles, and kinds of harmony...

 to the key

Key (music)

In music theory, the term key is used in many different and sometimes contradictory ways. A common use is to speak of music as being "in" a specific key, such as in the key of C major or in the key of F-sharp. Sometimes the terms "major" or "minor" are appended, as in the key of A minor or in the...

 of F major except the first.
In contrast, the vi-ii-V-I or circle progression

Circle progression

In music, the circle progression is a chord progression named for the circle of fifths, along which it travels. It is "undoubtedly the most common and the strongest of all harmonic progressions" and consists of "adjacent roots in ascending fourth or descending fifth relationship", with movement by...

 from classical theory contains four chords of two or three different qualities: major, minor, and possibly a dominant seventh chord

Dominant seventh chord

In music theory, a dominant seventh chord, or major minor seventh chord,is a chord composed of a root, major third, perfect fifth, and minor seventh. It can be also viewed as a major triad with an additional minor seventh...

; all of which, however, are diatonic to the key. Thus diversity is achieved within a stable and fixed tonal center.