Chord (music)

The chord progression vi–ii–V–I in the key of C major. Using lead sheet chord names, these chords could be referred to as A minor, D minor, G major and C major.[28]

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., vii^o7 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 specifies to the performer which string should be used with the Roman numeral. Alternately, the note name of the string that the composer wishes the performer to use are stated using letters (e.g., "sul G" means "play on the G string").

Common Conventional Symbols for Figured Bass

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	75 3	7
1st inversion	65 3	6 5
2nd inversion	64 3	4 3
3rd inversion	64 2	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.

can be realized as

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 for triads on C

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.[29]

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 an 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.

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.[30]
• 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 m^7(♭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. G^M7 or F^Δ7). 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., A^sus4(add9) or A^sus4(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., A^{sus2(add♭7)} or A^sus2(add4)).
• (♭9) (parenthesis) is used to indicate explicit chord alterations (e.g., A^7(♭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. C^7add13 is a C 7th chord plus an added 13th).
• alt or alt dom indicates an altered dominant seventh chord (e.g. G^7♯11).
• omit5 (or simply no5) indicates that the (indicated) note should be omitted.

The table below lists common chord types, their symbols, and their components.

Chord			Components
Name	Symbol (on C)		Interval	P1	m2	M2	m3	M3	P4	d5	P5	A5	M6/d7	m7	M7
	Short	Long	Semitones	0	1	2	3	4	5	6	7	8	9	10	11
Major triad	C CΔ			P1				M3			P5
Major sixth chord	C6 CM6	Cmaj6		P1				M3			P5		M6
Dominant seventh chord	C7	Cdom7		P1				M3			P5			m7
Major seventh chord	CM7 C∆7	Cmaj7		P1				M3			P5				M7
Augmented triad	C+	Caug		P1				M3				A5
Augmented seventh chord	C+7	Caug7		P1				M3				A5		m7
Minor triad	Cm	Cmin		P1			m3				P5
Minor sixth chord	Cm6	Cmin6		P1			m3				P5		M6
Minor seventh chord	Cm7	Cmin7		P1			m3				P5			m7
Minor-major seventh chord	CmM7 Cm/M7 Cm(M7)	Cminmaj7 Cmin/maj7 Cmin(maj7)		P1			m3				P5				M7
Diminished triad	Co	Cdim		P1			m3			d5
Diminished seventh chord	Co7	Cdim7		P1			m3			d5			d7
Half-diminished seventh chord	Cø Cø7			P1			m3			d5				m7

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 (jazz guitar, jazz piano, Hammond organ) 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 will indicate this explicitly with the indications "C⁷", "C^maj7" or "Cm⁷".

Two-note combinations, whether referred to as chords or intervals, are called dyads. In the context of a specific section in a piece of music, dyads can be heard as chords if they have the most important notes that identify a certain chord. For example, in a piece in C Major, after a section of tonic C Major chords, if a dyad containing the notes B and D is played, listeners will likely hear this as a first inversion G Major chord. Other dyads are more ambiguous, an aspect that composers can use creatively. For example, a dyad with a perfect fifth has no third, so it does not sound major or minor; a composer who ends a section on a perfect fifth could subsequently add the missing third. Another example is a dyad outlining the tritone, such as the notes C and F# in C Major. This dyad could be heard as implying a D7 chord (resolving to G Major) or as implying a C diminished chord (resolving to Db Major). In unaccompanied duos for two instruments, such as flute duos, the only combinations of notes that are possible are dyads, which means that all of the chord progressions must be implied through dyads, as well as with arpeggios.

Chords constructed of three notes of some underlying scale are described as triads. Chords of four notes are known as tetrads, those containing five are called pentads and those using six are hexads. Sometimes the terms trichord, tetrachord, pentachord, and hexachord are used—though these more usually refer to the pitch classes of any scale, not generally played simultaneously. Chords that may contain more than three notes include pedal point chords, dominant seventh chords, extended chords, added tone chords, clusters, and polychords.

Polychords are formed by two or more chords superimposed.[31] Often these may be analysed as extended chords; examples include tertian, altered chord, secundal chord, quartal and quintal harmony and Tristan chord. Another example is when G^7(♯11♭9) (G–B–D–F–A♭–C♯) is formed from G major (G–B–D) and D♭ major (D♭–F–A♭).[32] A nonchord tone is a dissonant or unstable tone that lies outside the chord currently heard, though often resolving to a chord tone.[33]

In the key of C major, the first degree of the scale, called the tonic, is the note C itself. A C major chord, the major triad built on the note C (C–E–G), is referred to as the one chord of that key and notated in Roman numerals as I. The same C major chord can be found in other scales: it forms chord III in the key of A minor (A→B→C) and chord IV in the key of G major (G→A→B→C). This numbering indicates the chords's function.

Many analysts use lower-case Roman numerals to indicate minor triads and upper-case numerals for major triads, and degree and plus signs ( ^o and ⁺ ) to indicate diminished and augmented triads respectively. Otherwise, all the numerals may be upper-case and the qualities of the chords inferred from the scale degree. Chords outside the scale can be indicated by placing a flat/sharp sign before the chord—for example, the chord E♭ major in the key of C major is represented by ♭III. The tonic of the scale may be indicated to the left (e.g. "F♯:") or may be understood from a key signature or other contextual clues. Indications of inversions or added tones may be omitted if they are not relevant to the analysis. Roman numeral analysis indicates the root of the chord as a scale degree within a particular major key as follows.

In the harmony of Western art music, a chord is in root position when the tonic note is the lowest in the chord (the bass note), and the other notes are above it. When the lowest note is not the tonic, the chord is inverted. Chords that have many constituent notes can have many different inverted positions as shown below for the C major chord:

Bass note	Position	Order of notes (starting from the bass)	Notation
C	root position	C–E–G or C–G–E	5 3 as G is a fifth above C and E is a third above C
E	first inversion	E–G–C or E–C–G	6 3 as C is a sixth above E and G is a third above E
G	second inversion	G–C–E or G–E–C	6 4 as E is a sixth above G and C is a fourth above G

Further, a four-note chord can be inverted to four different positions by the same method as triadic inversion. For example, a G⁷ chord can be in root position (G as bass note); first inversion (B as bass note); second inversion (D as bass note); or third inversion (F as bass note).

Where guitar chords are concerned, the term "inversion" is used slightly differently; to refer to stock fingering "shapes".[34]

Many chords are a sequence of notes separated by intervals of roughly the same size. Chords can be classified into different categories by this size:

• Tertian chords can be decomposed into a series of (major or minor) thirds. For example, the C major triad (C–E–G) is defined by a sequence of two intervals, the first (C–E) being a major third and the second (E–G) being a minor third. Most common chords are tertian.
• Secundal chords can be decomposed into a series of (major or minor) seconds. For example, the chord C–D–E♭ is a series of seconds, containing a major second (C–D) and a minor second (D–E♭).
• Quartal chords can be decomposed into a series of (perfect or augmented) fourths. Quartal harmony normally works with a combination of perfect and augmented fourths. Diminished fourths are enharmonically equivalent to major thirds, so they are uncommon.[35] For example, the chord C–F–B is a series of fourths, containing a perfect fourth (C–F) and an augmented fourth/tritone (F–B).

These terms can become ambiguous when dealing with non-diatonic scales, such as the pentatonic or chromatic scales. The use of accidentals can also complicate the terminology. For example, the chord B♯–E–A♭ appears to be quartal, as a series of diminished fourths (B♯–E and E–A♭), but it is enharmonically equivalent to (and sonically indistinguishable from) the tertian chord C–E–G♯, which is a series of major thirds (C–E and E–G♯).

The notes of a chord form intervals with each of the other notes of the chord in combination. A 3-note chord has 3 of these harmonic intervals, a 4-note chord has 6, a 5-note chord has 10, a 6-note chord has 15.[36] The absence, presence, and placement of certain key intervals plays a large part in the sound of the chord, and sometimes of the selection of the chord that follows.

A chord containing tritones is called tritonic; one without tritones is atritonic. Harmonic tritones are an important part of dominant seventh chords, giving their sound a characteristic tension, and making the tritone interval likely to move in certain stereotypical ways to the following chord.[37] Tritones are also present in diminished seventh and half-diminished chords.

A chord containing semitones, whether appearing as minor seconds or major sevenths, is called hemitonic; one without semitones is anhemitonic. Harmonic semitones are an important part of major seventh chords, giving their sound a characteristic high tension, and making the harmonic semitone likely to move in certain stereotypical ways to the following chord.[38] A chord containing major sevenths but no minor seconds is much less harsh in sound than one containing minor seconds as well.

Other chords of interest might include the

• Diminished triad, which has many minor thirds and no major thirds, many tritones but no perfect fifths
• Augmented triad, which has many major thirds and no minor thirds or perfect fifths
• Dominant seventh flat five chord, which has many major thirds and tritones and no minor thirds or perfect fifths

Triads, also called triadic chords, are tertian chords with three notes. The four basic triads are described below.

Type	Component intervals		Chord symbol	Notes	Audio
	Third	Fifth
Major triad	major	perfect	C, CM, Cmaj, CΔ, Cma	C E G	play
Minor triad	minor	perfect	Cm, Cmin, C−, Cmi	C E♭ G	play
Augmented triad	major	augmented	Caug, C+, C+	C E G♯	play
Diminished triad	minor	diminished	Cdim, Co, Cm(♭5)	C E♭ G♭	play

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 (e.g. Dm7, Dm⁷, and D^m7 are all identical).

Type	Component intervals			Chord symbol	Notes	Audio
	Third	Fifth	Seventh
Diminished seventh	minor	diminished	diminished	Co7, Cdim7	C E♭ G♭ B	Play
Half-diminished seventh	minor	diminished	minor	Cø7, Cm7♭5, C−(♭5)	C E♭ G♭ B♭	Play
Minor seventh	minor	perfect	minor	Cm7, Cmin7, C−7,	C E♭ G B♭	Play
Minor major seventh	minor	perfect	major	CmM7, Cmmaj7, C−(j7), C−Δ7, C−M7	C E♭ G B	Play
Dominant seventh	major	perfect	minor	C7, Cdom7	C E G B♭	Play
Major seventh	major	perfect	major	CM7, CM7, Cmaj7, CΔ7, Cj7	C E G B	Play
Augmented seventh	major	augmented	minor	C+7, Caug7, C7+, C7+5, C7♯5	C E G♯ B♭	Play
Augmented major seventh	major	augmented	major	C+M7, CM7+5, CM7♯5, C+j7, C+Δ7	C E G♯ B	Play

Extended chords are triads with further tertian notes added beyond the seventh: the ninth, eleventh, and thirteenth chords. For example, a dominant thirteenth chord consists of the notes C–E–G–B♭–D–F–A:

The upper structure or extensions, i.e. the notes beyond the seventh, are shown 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.

Type	Components				Chord symbol	Notes	Audio
	Chord	Extensions
Dominant ninth	dominant seventh	major ninth	—	—	C9	C E G B♭ D	Play
Dominant eleventh	dominant seventh (the third is usually omitted)	major ninth	perfect eleventh	—	C11	C E G B♭ D F	Play
Dominant thirteenth	dominant seventh	major ninth	perfect eleventh (usually omitted)	major thirteenth	C13	C E G B♭ D F A	Play

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.

An altered chord on C with a diminished fifth and a minor seventh and ninth.

The third and seventh of the chord are always determined by the symbols shown above. The root cannot be so altered without changing the name of the chord, while the third cannot be altered without altering the chord's quality. Nevertheless, the fifth, ninth, eleventh and thirteenth may all be chromatically altered by accidentals.

These are noted alongside the altered element. Accidentals are most often used with dominant seventh chords. Altered dominant seventh chords (C^7alt) may have a minor ninth, a sharp ninth, a diminished fifth, or an augmented fifth. Some write this as C⁷⁺⁹, which assumes also the minor ninth, diminished fifth and augmented fifth. The augmented ninth is often referred to in blues and jazz as a blue note, being enharmonically equivalent to the minor third or tenth. When superscripted numerals are used the different numbers may be listed horizontally or vertically.

Type	Components		Chord symbol	Notes	Audio
	Chord	Alteration
Seventh augmented fifth	dominant seventh	augmented fifth	C7+5, C7♯5	C E G♯ B♭	Play
Seventh minor ninth	dominant seventh	minor ninth	C7−9, C7♭9	C E G B♭ D♭	Play
Seventh sharp ninth	dominant seventh	augmented ninth	C7+9, C7♯9	C E G B♭ D♯	Play
Seventh augmented eleventh	dominant seventh	augmented eleventh	C7+11, C7♯11	C E G B♭ D F♯	Play
Seventh diminished thirteenth	dominant seventh	minor thirteenth	C7−13, C7♭13	C E G B♭ D F A♭	Play
Half-diminished seventh	minor seventh	diminished fifth	Cø, Cø7, Cm7♭5	C E♭ G♭ B♭	Play

A suspended chord (sus2) and added tone chord (add9) both with D (ninth = second), distinguished by the absence or presence of the third (E♭).[39]

An added tone chord is a triad with an added, non-tertian note, such as an added sixth or a chord with an added second (ninth) or fourth (eleventh) or a combination of the three. These chords do not include "intervening" thirds as in an extended chord. Added chords can also have variations. Thus, m^add9, m⁴ and m⁶ are minor triads with extended notes.

Sixth chords can belong to either of two groups. One is first inversion chords and added sixth chords that contain a sixth from the root.[40] The other group is inverted chords in which the interval of a sixth appears above a bass note that is not the root.[41]

The major sixth chord (also called, sixth or added sixth with the chord notation 6, e.g., C⁶) is by far the most common type of sixth chord of the first group. It comprises a major triad with the added major sixth above the root, common in popular music.[18] For example, the chord C⁶ contains the notes C–E–G–A. The minor sixth chord (min⁶ or m⁶, e.g., Cm⁶) is a minor triad, still with a major 6. For example, the chord Cm⁶ contains the notes C–E♭–G–A.

The augmented sixth chord usually appears in chord notation as its enharmonic equivalent, the seventh chord. This chord contains two notes separated by the interval of an augmented sixth (or, by inversion, a diminished third, though this inversion is rare). The augmented sixth is generally used as a dissonant interval most commonly used in motion towards a dominant chord in root position (with the root doubled to create the octave the augmented sixth chord resolves to) or to a tonic chord in second inversion (a tonic triad with the fifth doubled for the same purpose). In this case, the tonic note of the key is included in the chord, sometimes along with an optional fourth note, to create one of the following (illustrated here in the key of C major):

• Italian sixth chord: A♭, C, F♯
• French sixth chord: A♭, C, D, F♯
• German sixth chord: A♭, C, E♭, F♯

The augmented sixth family of chords exhibits certain peculiarities. Since they are not based on triads, as are seventh chords and other sixth chords, they are not generally regarded as having roots (nor, therefore, inversions), although one re-voicing of the notes is common (with the namesake interval inverted to create a diminished third).[42]

The second group of sixth chords includes inverted major and minor chords, which may be called sixth chords in that the six-three (⁶
₃) and six-four (⁶
₄) chords contain intervals of a sixth with the bass note, though this is not the root. Nowadays, this is mostly for academic study or analysis (see figured bass) but the Neapolitan sixth chord is an important example; a major triad with a flat supertonic scale degree as its root that is called a "sixth" because it is almost always found in first inversion. Though a technically accurate Roman numeral analysis would be ♭II, it is generally labelled N⁶. In C major, the chord is notated (from root position) D♭, F, A♭. Because it uses chromatically altered tones, this chord is often grouped with the borrowed chords but the chord is not borrowed from the relative major or minor and it may appear in both major and minor keys.

Type	Components			Chord symbol	Notes	Audio
	Chord	Interval(s)
Add nine	major triad	major ninth	—	C2, Cadd9	C E G D	Play
Add fourth	major triad	perfect fourth	—	C4, Cadd11	C E G F	Play
Add sixth	major triad	major sixth	—	C6	C E G A	Play
Six-nine	major triad	major sixth	major ninth	C6/9	C E G A D	—
Seven-six	major triad	major sixth	minor seventh	C7/6	C E G A B♭	—
Mixed-third	major triad	minor third	—	—	C E♭ E G	Play

A C^sus4 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, C^sus2 and C^sus4, 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 layman usage, the term is restricted to the displacement of the third only and the dissonant second or fourth no longer needs to be held over (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 C^7sus4. C^sus4 is sometimes written C^sus since the sus4 is more common than the sus2.

Type	Components				Chord symbol	Notes	Audio
	Chord	Interval(s)
Suspended second	open fifth	major second	—	—	Csus2	C D G	Play
Suspended fourth	open fifth	perfect fourth	—	—	Csus4	C F G	Play
Jazz sus	open fifth	perfect fourth	minor seventh	major ninth	C9sus4	C F G B♭ D	Play

Borrowed chords from the parallel minor key are commonly found in the Baroque, Classical and Romantic eras.

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 (e.g., 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 (e.g., a G major chord used in an E major song), the ♭VII chord (e.g., a D major chord used in an E major song) and the ♭VI chord (e.g., a C major chord used in an E major song). All of these chords are "borrowed" from the key of E minor.