Musicians use various kinds of chord names and symbols in different contexts to represent musical chords. In most genres of popular music, including jazz, pop, and rock, a chord name and its corresponding symbol typically indicate one or more of the following:
- the root note (e.g. C♯),
- the chord quality (e.g. minor or lowercase m, or the symbols o or + for diminished and augmented chords, respectively; chord quality is usually omitted for major chords),
- whether the chord is a triad, seventh chord, or an extended chord (e.g. Δ7),
- any altered notes (e.g. sharp five, or ♯5),
- any added tones (e.g. add2), and
- the bass note if it is not the root (e.g. a slash chord).
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For instance, the name C augmented seventh, and the corresponding symbol Caug7, or C+7, are both composed of parts 1 (letter 'C'), 2 ('aug' or '+'), and 3 (digit '7'). These indicate a chord formed by the notes C–E–G♯–B♭. The three parts of the symbol (C, aug, and 7) refer to the root C, the augmented (fifth) interval from C to G♯, and the (minor) seventh interval from C to B♭.
Although they are used occasionally in classical music, typically in an educational setting for harmonic analysis, these names and symbols are "universally used in jazz and popular music", in lead sheets, fake books, and chord charts, to specify the chords that make up the chord progression of a song or other piece of music. A typical sequence of a jazz or rock song in the key of C major might indicate a chord progression such as
- C – Am – Dm – G7.
This chord progression instructs the performer to play, in sequence, a C major triad, an A minor chord, a D minor chord, and a G dominant seventh chord. In a jazz context, players have the freedom to add sevenths, ninths, and higher extensions to the chord. In some pop, rock and folk genres, triads are generally performed unless specified in the chord chart.