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 european-influenced music. They may also be refered to as harmonic progressions.

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

Chord progressions are usually associated with a scale and the notes of each chord are usually taken from that scale. Melodies and other parts usually comply with the chord changes in that their notes are usually taken from the chord currently playing. Notes which are not taken from the chord are called nonchord tones and usually resolve quickly to a chord tone.

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.

{| border=1 cellpadding=5 cellspacing=0 |+Table of common progressions during the common practice period !colspan=4|Table of Common Progressions |- |I, i |colspan=3|May progress to any other triad. May interrupt any progression. |- !colspan=2|Major keys !colspan=2|Minor keys |- |rowspan=2|ii |rowspan=2|ii-V, ii-vii6° |ii6° |ii6°-V |- |ii* |ii-V, ii-vii6° |- |iii |iii-ii6, iii-IV, iii-V, iii-vi |III |III-ii6°, III-iv, III-VI |- |rowspan=2|IV |rowspan=2|IV-I, IV-ii, VI-V, IV-vii6° |iv |iv-i, iv-ii6°, iv-V, iv-VII |- |IV* |IV-V, IV-vii6° |- |rowspan=2|V |rowspan=2|V-I, V-vi |V |V-i, V-VI |- |v* |v-VI |- |vi |vi-ii, vi-IV, vi-V, vi-iii-IV |VI |VI-ii6°, VI-iv, VI-V, VI-III-iv |- |vii6° |vii6°-I |vii6°/VII |vii6°-i/VII-III |- |colspan=4|* ii and IV in minor used with an ascending #6; v in minor used with a descending 7. See the article chord (music) and chord symbol for an explanation of the notation used in this table. |}

Further reading