Chord progression

A chord progression, as its name implies, is a series of chordss played in sequence. Part and parcel of this action is the idea that the chords relate to each other in some way, whether closely or distantly, and they as a whole become an entity in themselves as a section, movement, or any other hypothetical name for a piece that to the ear can become familiar because of the harmonic progression used. Chord progressions are central to most modern music.

The most common chords are based on the first, fourth, and fifth scale degrees; see three chord song and Twelve bar blues.

The melody and harmony parts for a song usually comply with the chord changes; notes are taken from the chord's associated scale.

In music of the common practice period generally only certain chord progressions are used and many of the progressions not used are not traditionally tonal.

Chord progressions may also be refered to as harmonic progressions.

Reading

Walter Piston -- "Harmony," 1969. ISBN 0393954803.