Chord (music)

In Western music theory, a chord is a group of notes played together for their harmonic consonance or dissonance. The most basic type of chord is a triad, so called because it consists of three distinct notes: the root note along with intervals of a third and a fifth above the root note. Chords with more than three notes include added tone chords, extended chords and tone clusters, which are used in contemporary classical music, jazz, and other genres.

A guitarist performing a C chord with G bass

Chords are the building blocks of harmony and form the harmonic foundation of a piece of music. They provide the harmonic support and coloration that accompany melodies and contribute to the overall sound and mood of a musical composition. The factors, or component notes, of a chord are often sounded simultaneously but can instead be sounded consecutively, as in an arpeggio.

A succession of chords is called a chord progression. One example of a widely used chord progression in Western traditional music and blues is the 12 bar blues progression. Although any chord may in principle be followed by any other chord, certain patterns of chords are more common in Western music, and some patterns have been accepted as establishing the key (tonic note) in common-practice harmony—notably the resolution of a dominant chord to a tonic chord. To describe this, Western music theory has developed the practice of numbering chords using Roman numerals to represent the number of diatonic steps up from the tonic note of the scale.

Common ways of notating or representing chords in Western music (other than conventional staff notation) include Roman numerals, the Nashville Number System, figured bass, chord letters (sometimes used in modern musicology), and chord charts.

Quotes about chords in music

• A chord is by no means an agglomeration of intervals. It is a new unit which, although dependent on the formative power of the single interval, is felt as being self-existent and as giving to the constituent intervals meanings and functions which they otherwise would not have.
  • Paul Hindemith (1952: 72). A Composer's World. Cambridge, Mass.

• [Tonality is] the special meaning [functions] that chords receive through their relationship to a fundamental sonority, the tonic triad.
  • Hugo Riemann, cited in Gurlitt, W. (1950). Hugo Riemann (1849-1919).