A common chord, in the theory of harmony, is a chord that is

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

to more than one key or, in other words, is ''common'' to (shared by) two keys. A "common chord" may also be defined simply as a triadic chord (e.g., C–E–G), as one of the most commonly used chords in a key (I–IV–V–vi–ii), more narrowly as a triad in which the fifth is perfect (i.e., a major or minor triad), in which sense it is alternatively referred to as a "perfect chord" or, more narrowly still (in American practice), as a major triad only.Don Michael Randel, "Common Chord", ''Harvard Dictionary of Music'', fourth edition, Harvard University Press Reference Library 16 (Cambridge: Harvard University Press 2003): 193. . "Common chord: Major triad." Common chords are frequently used in modulations, in a type of modulation known as common chord modulation or diatonic pivot chord modulation. It moves from the original key to the destination key (usually a

closely related key In music, a closely related key (or close key) is one sharing many common tones with an original key, as opposed to a distantly related key (or distant key). In music harmony, there are six of them: five share all, or all except one, pitches wi ...

) by way of a chord both keys share. For example, G major and D major have 4 chords in common: G, Bm, D, Em. This can be easily determined by a chart similar to the one below, which compares chord qualities. The I chord in G major—a G major chord—is also the IV chord in D major, so I in G major and IV in D major are aligned on the chart. Any chord with the same

root note In music theory, the concept of root is the idea that a chord can be represented and named by one of its notes. It is linked to harmonic thinking—the idea that vertical aggregates of notes can form a single unit, a chord. It is in this sens ...

and chord quality can be used as the "pivot chord." However, chords that are not generally found in the style of the piece (for example, major VII chords in a Bach-style chorale) are also not likely to be chosen as the pivot chord. The most common pivot chords are the

predominant chord In music theory, a predominant chord (also pre-dominant) is any chord which normally resolves to a dominant chord.Benward & Saker (2009). ''Music in Theory and Practice: Volume II'', Glossary, p.359. Eighth Edition. . "Any chord in functional ...

s (ii and IV) in the new key. When analyzing a piece that uses this style of modulation, the common chord is labeled with its function in both the original and the destination keys, as it can be seen either way. A chord is common to, or shared by, six keys: three major keys, and three relative minor keys. For example, a C major chord is contained in F, C, and G major as well as D, A, and E minor.

Related keys

The number of diatonically occurring chords that two keys share is a measure of how closely related they are. A

can be defined as one that has many common chords. A relative major or minor key has all of its chords in common; a dominant or

subdominant In music, the subdominant is the fourth tonal degree () of the diatonic scale. It is so called because it is the same distance ''below'' the tonic as the dominant is ''above'' the tonicin other words, the tonic is the dominant of the subdomina ...

key has four in common. Less closely related keys have two or fewer chords in common. For example, C major and A minor have 7 common chords while C major and F major have 0 common chords.

References

{{DEFAULTSORT:Common Chord (Music) Chords Harmony

Related keys

See also

References