Chord (music): definition, structure, and uses

Structure and common types

Chords are built from intervals — the pitch distances between notes — arranged in a particular order called a voicing. The simplest widely used chords are triads, formed by stacking two thirds: the 1st, 3rd and 5th scale degrees produce the tonic triad in a key; when those scale degrees come from a major scale the triad is major, and from a minor scale it is minor. See a basic explanation of scale degrees at scale and degree and of major/minor quality at major and minor scales.

Beyond triads, common categories include seventh chords (adding the 7th above the root), extended chords (9ths, 11ths, 13ths), suspended chords (which replace the third with a 2nd or 4th), and altered chords (with modified fifths or ninths). Two-note combinations are often called dyads or, on string instruments, double stops. Theoretical labels (e.g., Cmaj7, Dm9, G7b9) indicate root, chord quality, and any added or altered tones.

How chords are played

Chords can be produced in many ways depending on the instrument. Keyboard instruments like the piano, electric keyboard and organ allow simultaneous pressing of multiple notes. Plucked instruments such as the guitar, ukulele and harp form chords by sounding several strings together. Some melody instruments are primarily monophonic but can supply harmonic support: the harmonica and various wind players can produce multiphonics or isolated intervals, while bowed strings use double stops to sustain two notes. A general list of chord-capable instruments is available at instruments overview.

• Piano
• Keyboard
• Organ
• Harp
• Guitar
• Harmonica
• Ukulele
• Xylophone

Bowing two strings simultaneously produces sustained dyads; skilled string players can imply multi-voice harmony by rapid alternation between string pairs. Some wind and brass players use specialized techniques to sound two harmonics at once; see extended playing techniques for examples.

History, function and examples

Chords as a systematic language developed gradually in Western art music from medieval organum through the modal harmony of the Renaissance to the tonal system of the Baroque and Classical eras, which emphasized functional progressions (tonic, dominant, subdominant). Later styles expanded harmonic vocabulary with chromaticism, extended and altered chords, and non-triadic approaches in jazz, folk, and contemporary music.

Functionally, chords provide harmonic context for melodies: they establish keys, create tension and release, color emotional content, and drive form through progressions. Simple examples include a common I–IV–V progression in popular music or a ii–V–I cadence in jazz. Understanding chord construction and voicing is central to composition, arranging, improvisation and accompaniment.

Notable distinctions and facts

While the textbook definition may vary by tradition, a few practical distinctions help performers and theorists: dyads versus triads, close versus open voicing, root position versus inversions, and harmonic function versus coloristic use. Chords also appear in many tuning systems and non-Western musical practices with different intervallic bases and names.

For further reading, follow introductory links above or consult specialized texts on harmony and instrument technique to hear examples and see notation of common chord types.