A | B | C | D | E | F | G | H | CH | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
In music, a chord is a group of two or more notes played simultaneously, typically consisting of a root note, a third, and a fifth.[a] Chords are the building blocks of harmony and form the harmonic foundation of a piece of music. They can be major, minor, diminished, augmented, or extended, depending on the intervals between the notes and their arrangement. Chords provide the harmonic support and coloration that accompany melodies and contribute to the overall sound and mood of a musical composition. For many practical and theoretical purposes, arpeggios and other types of broken chords (in which the chord tones are not sounded simultaneously) may also be considered as chords in the right musical context.
In tonal Western classical music (music with a tonic key or "home key"), the most frequently encountered chords are triads, so called because they consist of three distinct notes: the root note, and 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 almost any other genre.
A series of chords is called a chord progression.[1] 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[2] to represent the number of diatonic steps up from the tonic note of the scale.
Common ways of notating or representing chords[3] 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.
Definition
The English word chord derives from Middle English cord, a back-formation of accord[4] in the original sense of agreement and later, harmonious sound.[5] A sequence of chords is known as a chord progression or harmonic progression. These are frequently used in Western music.[6] A chord progression "aims for a definite goal" of establishing (or contradicting) a tonality founded on a key, root or tonic chord.[2] The study of harmony involves chords and chord progressions and the principles of connection that govern them.[7]
Ottó Károlyi[9] writes that, "Two or more notes sounded simultaneously are known as a chord," though, since instances of any given note in different octaves may be taken as the same note, it is more precise for the purposes of analysis to speak of distinct pitch classes. Furthermore, as three notes are needed to define any common chord, three is often taken as the minimum number of notes that form a definite chord.[10] Hence, Andrew Surmani, for example, states, "When three or more notes are sounded together, the combination is called a chord."[11] George T. Jones agrees: "Two tones sounding together are usually termed an interval, while three or more tones are called a chord."[12] According to Monath, "a chord is a combination of three or more tones sounded simultaneously", and the distances between the tones are called intervals.[13] However, sonorities of two pitches, or even single-note melodies, are commonly heard as implying chords.[14] 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.
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.[8]
History
In the medieval era, early Christian hymns featured organum (which used the simultaneous perfect intervals of a fourth, a fifth, and an octave[15]), with chord progressions and harmony - an incidental result of the emphasis on melodic lines during the medieval and then Renaissance (15th to 17th centuries).[16][17]
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.[3] It was in the Baroque period that the accompaniment of melodies with chords was developed, as in figured bass,[17] and the familiar cadences (perfect authentic, etc.).[18] In the Renaissance, certain dissonant sonorities that suggest the dominant seventh occurred with frequency.[19] In the Baroque period, the dominant seventh proper was introduced and was in constant use in the Classical and Romantic periods.[19] The leading-tone seventh appeared in the Baroque period and remains in use.[20] 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.[21]
The Romantic period, the 19th century, featured increased chromaticism.[3] Composers began to use secondary dominants in the Baroque, and they became common in the Romantic period.[22] Many contemporary popular Western genres continue to rely on simple diatonic harmony, though far from universally:[23] notable exceptions include the music of film scores, which often use chromatic, atonal or post-tonal harmony, and modern jazz (especially c. 1960), in which chords may include up to seven notes (and occasionally more).[24] 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"[citation needed].
Chords are also used for timbre effects. In organ registers, certain chords are activated by a single key so that 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 #5 the parallel parts of flutes, horn and celesta, being tuned as a chord, resemble the sound of an electric organ.[25][26]
Notation
Chords can be represented in various ways. The most common notation systems are:[3]
- Plain staff notation, used in classical music
- Roman numerals, commonly used in harmonic analysis to denote the scale step on which the chord is built.[2]
- Figured bass, much used in the Baroque era, uses numbers added to a bass line written on a staff, to enable keyboard players to improvise chords with the right hand while playing the bass with their left.
- Chord letters, sometimes used in modern musicology, to denote chord root and quality.
- Various chord names and symbols used in popular music lead sheets, fake books, and chord charts, to quickly lay out the harmonic ground plan of a piece so that the musician may improvise, jam, or vamp on it.
Roman numerals
While scale degrees are typically represented in musical analysis or musicology articles with Arabic numerals (e.g., 1, 2, 3, ..., sometimes with a circumflex above the numeral: 
, 
, 
, ...), the triads (three-note chords) that have these degrees as their roots are often identified by Roman numerals (e.g., I, IV, V, which in the key of C major would be the triads C major, F major, G major).
In some conventions (as in this and related articles) upper-case Roman numerals indicate major triads (e.g., I, IV, V) while lower-case Roman numerals indicate minor triads (e.g., I for a major chord and i for a minor chord, or using the major key, ii, iii and vi representing typical diatonic minor triads); other writers (e.g., 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 (e.g., viio7 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 (e.g., 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—e.g., "sul G" means "play on the G string".
Figured bass notation
| Triads | |||
|---|---|---|---|
| Inversion | Intervals above bass |
Symbol | Example |
| Root position | 5 3 |
None |  |
| 1st inversion | 6 3 |
6 | |
| 2nd inversion | 6 4 |
6 4 | |
| Seventh chords | |||
| Inversion | Intervals above bass |
Symbol | Example |
| Root position | 7 |  | |
| 1st inversion | 6 5 | ||
| 2nd inversion | 4 3 | ||
| 3rd inversion | 4 2 or 2 | ||
Figured bass or thoroughbass is a kind of musical notation used in almost all Baroque music (c. 1600–1750), 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.
For example, in the figured bass below, the bass note is a C, and the numbers 4 and 6 indicate that notes a fourth and a sixth above (F and A) should be played, giving the second inversion of the F major triad.
If no numbers are written beneath a bass note, the figure is assumed to be 5
3, 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.
Chord letters
Chord letters are used by musicologists, music theorists and advanced university music students to analyze songs and pieces. Chord letters use upper-case and lower-case letters to indicate the roots of chords, followed by symbols that specify the chord quality.[28]
Notation in popular music
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 (e.g., electric guitar, acoustic guitar, piano, Hammond organ, etc.) 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 (e.g., C).
- A symbol or abbreviation indicating the chord quality (e.g., minor, aug or o ). If no chord quality is specified, the chord is assumed to be a major triad by default.
- Number(s) indicating the stacked intervals above the root note (e.g., 7 or 13).
- Additional musical symbols or abbreviations for special alterations (e.g., ♭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 F/C, which sometimes get mixed up with slash chords.
Chord qualities are related with the qualities of the component intervals that define the chord. The main chord qualities are:
- Major and minor (a chord is "Major" by default and altered with added info: "C" = C major, "Cm" = c minor).
- augmented, diminished, and half-diminished,
- dominant seventh.
Symbols
The symbols used for notating chords are:
- m, min, or − indicates a minor chord. The "m" must be lowercase to distinguish it from the "M" for major.
- M, Ma, Maj, Δ, 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 indicates an augmented chord (A or a is not used).
- o or dim indicates a diminished chord, either a diminished triad or a diminished seventh chord (d is not used).
- ø 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 (e.g., 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 (e.g., add4, sus4).
- 5 is the (perfect) fifth of the chord and is only written as a number when altered (e.g., 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 Δ7 is indicated, this is a major 7th chord (e.g., GM7 or FΔ7). 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 (e.g., 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 (e.g., Asus2(add♭7) or Asus2(add4)).
- (♭9) (parenthesis) is used to indicate explicit chord alterations (e.g., 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. (e.g., C7add13 is a C 7th chord plus an added 13th).
- alt or alt dom indicates an altered dominant seventh chord (e.g., G7♯11).
- omit5 (or simply no5) indicates that the (indicated) note should be omitted.
Examples
The table below lists common chord types, their symbols, and their components.