Chord (music): the story on HearLore

Chord (music)

The word chord derives from the Middle English cord, a back-formation of accord, originally meaning agreement or harmonious sound. In Western music theory, a chord is defined as 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. While two notes sounding together are usually termed an interval, three or more tones are called a chord. This three-note minimum is often taken as the threshold for a definite chord, though instances of any given note in different octaves may be taken as the same note. Since a chord may be understood as such even when all its notes are not simultaneously audible, there has been some academic discussion regarding the point at which a group of notes may be called a chord. Jean-Jacques Nattiez explains that, "We can encounter 'pure chords' in a musical work", such as in the "Promenade" of Modest Mussorgsky's Pictures at an Exhibition but, "often, we must go from a textual given to a more abstract representation of the chords being used", as in Claude Debussy's Première arabesque. A simple example of two notes being interpreted as a chord is when the root and third are played but the fifth is omitted. In the key of C major, if the music stops on the two notes G and B, most listeners hear this as a G major chord.

From Church Organum to Baroque Harmony

Chords evolved out of the early church organum, which reflected the different vocal ranges. In its earliest written form, found in the treatise Musica enchiriadis around the year 900, organum consisted of two melodic lines moving simultaneously note against note. Organum was further developed with the staff notation established by monk Guido d'Arezzo around the year 1025. In the medieval era, early Christian hymns featured organum, which used the simultaneous perfect intervals of a fourth, a fifth, and an octave, with chord progressions and harmony as an incidental result of the emphasis on melodic lines during the medieval and then Renaissance periods from the 15th to the 17th centuries. The Baroque period, the 17th and 18th centuries, began to feature the major and minor scale based tonal system and harmony, including chord progressions and circle progressions. It was in the Baroque period that the accompaniment of melodies with chords was developed, as in figured bass, and the familiar cadences, such as perfect authentic and plagal cadences. In the Renaissance, certain dissonant sonorities that suggest the dominant seventh occurred with frequency. In the Baroque period, the dominant seventh proper was introduced and was in constant use in the Classical and Romantic periods. The leading-tone seventh appeared in the Baroque period and remains in use. Composers began to use nondominant seventh chords in the Baroque period. They became frequent in the Classical period, gave way to altered dominants in the Romantic period, and underwent a resurgence in the Post-Romantic and Impressionistic period. The Romantic period, the 19th century, featured increased chromaticism. Composers began to use secondary dominants in the Baroque, and they became common in the Romantic period. Many contemporary popular Western genres continue to rely on simple diatonic harmony, though far from universally: notable exceptions include the music of film scores, which often use chromatic, atonal or post-tonal harmony, and modern jazz, in which chords may include up to seven notes and occasionally more. When referring to chords that do not function as harmony, such as in atonal music, the term "sonority" is often used specifically to avoid any tonal implications of the word "chord".

Common questions

What is the definition of a chord in Western music theory?

A chord is defined as a group of notes played together for their harmonic consonance or dissonance. The most basic type of chord is a triad, which consists of three distinct notes: the root note along with intervals of a third and a fifth above the root note. While two notes sounding together are usually termed an interval, three or more tones are called a chord.

When did the Baroque period begin and how did it change chord usage?

The Baroque period began in the 17th century and continued through the 18th century. This era introduced the major and minor scale based tonal system and harmony, including chord progressions and circle progressions. It was in the Baroque period that the accompaniment of melodies with chords was developed, as in figured bass, and the familiar cadences, such as perfect authentic and plagal cadences.

Which chords were the most commonly used in a 2025 analysis of 52 million chords?

How are chords represented using Roman numerals in music analysis?

Roman numerals are commonly used in harmonic analysis to denote the scale step on which the chord is built. In some conventions, upper-case Roman numerals indicate major triads, such as I, IV, V, while lower-case Roman numerals indicate minor triads, such as i for a minor chord, or ii, iii and vi representing typical diatonic minor triads. Diminished triads may be represented by lower-case Roman numerals with a degree symbol, such as vii7 indicates a diminished seventh chord built on the seventh scale degree.

What is the difference between a suspended second chord and a suspended fourth chord?

A suspended second chord consists of an open fifth and a major second, such as Csus2, with notes C, D, G. A suspended fourth chord consists of an open fifth and a perfect fourth, such as Csus4, with notes C, F, G. The term suspended chord refers to a chord in which the third is replaced by either the second or the fourth.

The Modern Chord Frequency Study

A 2025 analysis of 52 million chords across 680,000 songs found that G major and C major were the most commonly used chords, accounting for 24% of all chords. These were followed by D major, A major, and F major. The study also observed a decline in chord diversity over time, with songs containing fewer unique chords and a decreasing ratio of unique chords to total chords. This ratio fell from 13% in the 1930s to 8% in the 2020s, indicating a trend toward more straightforward chord progressions in popular music. Chords are also used for timbre effects. In organ registers, certain chords are activated by a single key, so playing a melody results in parallel voice leading. These voices, losing independence, are fused into one with a new timbre. The same effect is also used in synthesizers and orchestral arrangements; for instance, in Ravel's Bolero number 5, the parallel parts of flutes, horn and celesta, being tuned as a chord, resemble the sound of an electric organ. The basic function of chord symbols is to eliminate the need to write out sheet music. The modern jazz player has extensive knowledge of the chordal functions and can mostly play music by reading the chord symbols only. Advanced chords are common especially in modern jazz. Altered 9ths, 11ths and 5ths are not common in pop music. In jazz, a chord chart is used by comping musicians, such as jazz guitar, jazz piano, and Hammond organ players, to improvise a chordal accompaniment and to play improvised solos. Jazz bass players improvise a bassline from a chord chart. Chord charts are used by horn players and other solo instruments to guide their solo improvisations. Interpretation of chord symbols depends on the genre of music being played. In jazz from the bebop era or later, major and minor chords are typically realized as seventh chords even if only "C" or "Cm" appear in the chart. In jazz charts, seventh chords are often realized with upper extensions, such as the ninth, sharp eleventh, and thirteenth, even if the chart only indicates "A7". In jazz, the root and fifth are often omitted from chord voicings, except when there is a diminished fifth or an augmented fifth. In a pop or rock context, however, "C" and "Cm" would almost always be played as triads, with no sevenths. In pop and rock, in the relatively less common cases where songwriters wish a dominant seventh, major seventh, or minor seventh chord, they indicate this explicitly with the indications "C7", "Cmaj7" or "Cm7".

The Language of Roman Numerals

Chords can be represented in various ways. The most common notation systems include plain staff notation, used in classical music, and Roman numerals, commonly used in harmonic analysis to denote the scale step on which the chord is built. While scale degrees are typically represented in musical analysis or musicology articles with Arabic numerals, such as 1, 2, 3, sometimes with a circumflex above the numeral, the triads that have these degrees as their roots are often identified by Roman numerals, such as I, IV, V, which in the key of C major would be the triads C major, F major, and G major. In some conventions, upper-case Roman numerals indicate major triads, such as I, IV, V, while lower-case Roman numerals indicate minor triads, such as i for a minor chord, or ii, iii and vi representing typical diatonic minor triads. Other writers, such as Schoenberg, use upper case Roman numerals for both major and minor triads. Some writers use upper-case Roman numerals to indicate the chord is diatonic in the major scale, and lower-case Roman numerals to indicate that the chord is diatonic in the minor scale. Diminished triads may be represented by lower-case Roman numerals with a degree symbol, such as vii7 indicates a diminished seventh chord built on the seventh scale degree; in the key of C major, this chord would be B diminished seventh, which consists of the notes B, D, F and A. Roman numerals can also be used in stringed instrument notation to indicate the position or string to play. In some string music, the string on which it is suggested that the performer play the note is indicated with a Roman numeral, such as on a four-string orchestral string instrument, I indicates the highest-pitched, thinnest string and IV indicates the lowest-pitched, thickest bass string. In some orchestral parts, chamber music and solo works for string instruments, the composer tells the performer which string to use with the Roman numeral. Alternately, the composer starts the note name with the string to use, such as "sul G" means "play on the G string". Figured bass or thoroughbass is a kind of musical notation used in almost all Baroque music from 1600 to 1750, though rarely in music from later than 1750, to indicate harmonies in relation to a conventionally written bass line. Figured bass is closely associated with chord-playing basso continuo accompaniment instruments, which include harpsichord, pipe organ and lute. Added numbers, symbols, and accidentals beneath the staff indicate the intervals above the bass note to play; that is, the numbers stand for the number of scale steps above the written note to play the figured notes. If no numbers are written beneath a bass note, the figure is assumed to be 1, which calls for a third and a fifth above the bass note, i.e., a root position triad. In the 2010s, some classical musicians who specialize in music from the Baroque era can still perform chords using figured bass notation; in many cases, however, the chord-playing performers read a fully notated accompaniment that has been prepared for the piece by the music publisher. Such a part, with fully written-out chords, is called a "realization" of the figured bass part.

The Symbolic Alphabet of Jazz

In most genres of popular music, including jazz, pop, and rock, a chord name and the corresponding symbol are typically composed of one or more parts. In these genres, chord-playing musicians in the rhythm section, such as electric guitar, acoustic guitar, piano, and Hammond organ, typically improvise the specific "voicing" of each chord from a song's chord progression by interpreting the written chord symbols appearing in the lead sheet or fake book. Normally, these chord symbols include a big letter indicating the root note, such as C, a symbol or abbreviation indicating the chord quality, such as minor, aug or, if no chord quality is specified, the chord is assumed to be a major triad by default, numbers indicating the stacked intervals above the root note, such as 7 or 13, and additional musical symbols or abbreviations for special alterations, such as 5, 5 or add13. An added slash / and an upper case letter indicates that a bass note other than the root should be played. These are called slash chords. For instance, C/F indicates that a C major triad should be played with an added F in the bass. In some genres of modern jazz, two chords with a slash between them may indicate an advanced chord type called a polychord, which is the playing of two chords simultaneously. The correct notation of this should be, which sometimes get mixed up with slash chords. The symbols used for notating chords include m, min, or - to indicate a minor chord. The "m" must be lowercase to distinguish it from the "M" for major. M, Ma, Maj, or (no symbol) indicates a major chord. In a jazz context, this typically indicates that the player should use any suitable chord of a major quality, for example a major seventh chord or a 6/9 chord. In a lot of jazz styles, an unembellished major triad is rarely if ever played, but in a lead sheet the choice of which major quality chord to use is left to the performer. + or aug or indicates an augmented chord. A or a is not used. or dim indicates a diminished chord, either a diminished triad or a diminished seventh chord. d is not used. indicates a half-diminished seventh chord. In some fake books, the abbreviation m7(5) is used as an equivalent symbol. 2 is mostly used as an extra note in a chord, such as add2, sus2. 3 is the minor or major quality of the chord and is rarely written as a number. 4 is mostly used as an extra note in a chord, such as add4, sus4. 5 is the (perfect) fifth of the chord and is only written as a number when altered, such as F7(5). In guitar music, like rock, a "5" indicates a power chord, which consists of only the root and fifth, possibly with the root doubled an octave higher. 6 indicates a sixth chord. There are no rules if the 6 replaces the 5th or not. 7 indicates a dominant seventh chord. However, if Maj7, M7 or 7 is indicated, this is a major 7th chord, such as G or F. Very rarely, also dom is used for dominant 7th. 9 indicates a ninth chord, which in jazz usually includes the dominant seventh as well, if it is a dominant chord. 11 indicates an eleventh chord, which in jazz usually includes the dominant seventh and ninth as well, if it is a dominant chord. 13 indicates a thirteenth chord, which in jazz usually includes the dominant seventh, ninth and eleventh as well. 6/9 indicates a triad with the addition of the sixth and ninth. sus4 or simply 4 indicates a sus chord with the third omitted and the fourth used instead. Other notes may be added to a sus4 chord, indicated with the word "add" and the scale degree, such as Asus4(add9) or Asus4(add7). sus2 or simply 2 indicates a sus chord with the third omitted and the second, which may also be called the ninth, used instead. As with "sus4", a "sus2" chord can have other scale degrees added, such as Asus2(add7) or Asus2(add4). Parenthesis is used to indicate explicit chord alterations, such as A7(9). The parenthesis is probably left from older days when jazz musicians weren't used to "altered chords". Albeit important, the parenthesis can be left unplayed with no "musical harm". add indicates that an additional interval number should be added to the chord, such as C7add13 is a C 7th chord plus an added 13th. alt or alt dom indicates an altered dominant seventh chord, such as G711. omit5 or simply no5 indicates that the indicated note should be omitted.

The Architecture of Triads and Tetrads

Triads, also called triadic chords, are tertian chords with three notes. The four basic triads are described below. A major triad consists of a major third and a perfect fifth, such as C, CM, Cmaj, C, Cma, with notes C, E, G. A minor triad consists of a minor third and a perfect fifth, such as Cm, Cmin, C-, Cmi, with notes C, E, G. An augmented triad consists of a major third and an augmented fifth, such as Caug, C, C+, with notes C, E, G. A diminished triad consists of a minor third and a diminished fifth, such as Cdim, C, Cm(5), with notes C, E, G. Seventh chords are tertian chords, constructed by adding a fourth note to a triad, at the interval of a third above the fifth of the chord. This creates the interval of a seventh above the root of the chord, the next natural step in composing tertian chords. The seventh chord built on the fifth step of the scale, the dominant seventh, is the only dominant seventh chord available in the major scale: it contains all three notes of the diminished triad of the seventh and is frequently used as a stronger substitute for it. There are various types of seventh chords depending on the quality of both the chord and the seventh added. In chord notation the chord type is sometimes superscripted and sometimes not, such as Dm7, Dm7, and Dm7 are all identical. A diminished seventh chord consists of a minor third, a diminished fifth, and a diminished seventh, such as C7, Cdim7, with notes C, E, G, B. A half-diminished seventh chord consists of a minor third, a diminished fifth, and a minor seventh, such as C7, Cm75, with notes C, E, G, B. A minor seventh chord consists of a minor third, a perfect fifth, and a minor seventh, such as Cm7, Cmin7, with notes C, E, G, B. A minor major seventh chord consists of a minor third, a perfect fifth, and a major seventh, such as CmM7, with notes C, E, G, B. A dominant seventh chord consists of a major third, a perfect fifth, and a minor seventh, such as C7, Cdom7, with notes C, E, G, B. A major seventh chord consists of a major third, a perfect fifth, and a major seventh, such as CM7, CM7, Cmaj7, C7, Cj7, with notes C, E, G, B. An augmented seventh chord consists of a major third, an augmented fifth, and a minor seventh, such as C+7, Caug7, C7+, C7+5, C75, with notes C, E, G, B. An augmented major seventh chord consists of a major third, an augmented fifth, and a major seventh, such as C+M7, CM7+5, CM75, C+j7, C+7, with notes C, E, G, B. Extended chords are triads with further tertian notes added beyond the seventh: the ninth, eleventh, and thirteenth chords. For example, a minor eleventh chord such as Am11 consists of the notes A, C, E, G, B, D. The upper structure or extensions, i.e., notes beyond the seventh, are shown here in red. This chord is just a theoretical illustration of this chord. In practice, a jazz pianist or jazz guitarist would not normally play the chord all in thirds as illustrated. Jazz voicings typically use the third, seventh, and then the extensions such as the ninth and thirteenth, and in some cases the eleventh. The root is often omitted from chord voicings, as the bass player will play the root. The fifth is often omitted if it is a perfect fifth. Augmented and diminished fifths are normally included in voicings. After the thirteenth, any notes added in thirds duplicate notes elsewhere in the chord; all seven notes of the scale are present in the chord, so adding more notes does not add new pitch classes. Such chords may be constructed only by using notes that lie outside the diatonic seven-note scale. A dominant ninth chord consists of a dominant seventh and a major ninth, such as C9, with notes C, E, G, B, D. A dominant eleventh chord consists of a dominant seventh, a major ninth, and a perfect eleventh, such as C11, with notes C, E, G, B, D, F. A dominant thirteenth chord consists of a dominant seventh, a major ninth, a perfect eleventh, and a major thirteenth, such as C13, with notes C, E, G, B, D, F, A. Other extended chords follow similar rules, so that for example maj9, maj11, and maj13 contain major seventh chords rather than dominant seventh chords, while m9, m11, and m13 contain minor seventh chords.

The Suspended and Borrowed Chord

A suspended chord, or "sus chord", is a chord in which the third is replaced by either the second or the fourth. This produces two main chord types: the suspended second, sus2, and the suspended fourth, sus4. The chords, Csus2 and Csus4, for example, consist of the notes C, D, G and C, F, G, respectively. There is also a third type of suspended chord, in which both the second and fourth are present, for example the chord with the notes C, D, F, G. The name suspended derives from an early polyphonic technique developed during the common practice period, in which a stepwise melodic progress to a harmonically stable note in any particular part was often momentarily delayed, or suspended, by extending the duration of the previous note. The resulting unexpected dissonance could then be all the more satisfyingly resolved by the eventual appearance of the displaced note. In traditional music theory, the inclusion of the third in either chord would negate the suspension, so such chords would be called added ninth and added eleventh chords instead. In modern lay usage, the term is restricted to the displacement of the third only, and the dissonant second or fourth no longer must be held over, or prepared, from the previous chord. Neither is it now obligatory for the displaced note to make an appearance at all, though in the majority of cases the conventional stepwise resolution to the third is still observed. In post-bop and modal jazz compositions and improvisations, suspended seventh chords are often used in nontraditional ways: these often do not function as V chords and do not resolve from the fourth to the third. The lack of resolution gives the chord an ambiguous, static quality. Indeed, the third is often played on top of a sus4 chord. A good example is the jazz standard, "Maiden Voyage". Extended versions are also possible, such as the seventh suspended fourth, which, with root C, contains the notes C, F, G, B and is notated as C7sus4. Csus4 is sometimes written Csus since the sus4 is more common than the sus2. A suspended second chord consists of an open fifth and a major second, such as Csus2, with notes C, D, G. A suspended fourth chord consists of an open fifth and a perfect fourth, such as Csus4, with notes C, F, G. A jazz sus chord consists of an open fifth, a perfect fourth, a minor seventh, and a major ninth, such as C9sus4, with notes C, F, G, B, D. A borrowed chord is one from a different key than the home key, the key of the piece it is used in. The most common occurrence of this is where a chord from the parallel major or minor key is used. Particularly good examples can be found throughout the works of composers such as Schubert. For instance, for a composer working in the C major key, a major III chord, such as an E major chord, would be borrowed, as this chord appears only in the key of C minor. Although borrowed chords could theoretically include chords taken from any key other than the home key, this is not how the term is used when a chord is described in formal musical analysis. When a chord is analysed as "borrowed" from another key it may be shown by the Roman numeral corresponding with that key after a slash. For example, V/V, pronounced "five of five", indicates the dominant chord of the dominant key of the present home-key. The dominant key of C major is G major so this secondary dominant is the chord of the fifth degree of the G major scale, which is D major, which can also be described as II relative to the key of C major, not to be confused with the supertonic ii namely D minor. If used for a significant duration, the use of the D major chord may cause a modulation to a new key, in this case to G major. Borrowed chords are widely used in Western popular music and rock music. For example, there are a number of songs in E major which use the III chord, such as a G major chord used in an E major song, the VII chord, such as a D major chord used in an E major song, and the VI chord, such as a C major chord used in an E major song. All of these chords are "borrowed" from the key of E minor. A bell chord, also known colloquially as "bells", is a musical arrangement technique in which a composition has separate instruments, or multiples of the same instrument, play single notes of a chord in sequence, sustaining individual notes to form the chord. It is, in effect, an arpeggio played by several instruments sequentially. This is also known as a pyramid or cascade. It is common in barbershop music. The technique originated with jazz big bands and is a staple of trad jazz. A good example can be heard in the introduction to "The Charleston" by The Temperance Seven. "Bohemian Rhapsody" by the rock band Queen contains two occurrences of this "bell effect" in the middle section, as does the solo in "Killer Queen" starting at 1:48.