What are chords and what do they do?

What is a chord?

A chord combines notes into a harmony. In C major, stacking thirds on each scale degree gives C major (C–E–G), D minor (D–F–A), E minor (E–G–B), F major (F–A–C), G major (G–B–D), A minor (A–C–E), and B diminished (B–D–F).

4 types of chords

The four basic triad qualities are major, minor, diminished and augmented. Their intervals determine their quality. Roman numerals describe a chord’s root and quality relative to a key; they are not the only way to name chords.

What is the differance between a triad and a seventh chords?

A triad has three different notes that can be arranged as a root, third and fifth. A seventh chord adds a fourth note: a seventh above the root.

Types of Chords

Major Triad Chord

A major triad contains a root, a major third and a perfect fifth. C major is C–E–G: E is four semitones above C, and G is seven semitones above C.

Major Seventh Chord

A major seventh chord combines a major triad with a major seventh above its root. Cmaj7 is C–E–G–B. Using B-flat instead gives C7, a dominant seventh chord.

Minor Triad Chord

A minor triad contains a root, a minor third and a perfect fifth. F minor is F–A-flat–C. Both intervals are measured from the root, F.

Minor Seventh Chord

A minor seventh chord combines a minor triad with a minor seventh above the root. Dm7 is D–F–A–C. It differs from D7, which has F-sharp and is a dominant seventh chord.

Augmented Triad Chord

An augmented triad contains a root, a major third and an augmented fifth. C augmented is C–E–G-sharp, often written Caug or C+.

Augmented Seventh Chord

An augmented seventh chord, commonly written C7(#5) or C+7, adds a minor seventh to an augmented triad: C–E–G-sharp–B-flat. Cmaj7(#5) instead has B natural, a major seventh.

Diminished Triad Chords

A diminished triad contains a root, minor third and diminished fifth. B diminished is B–D–F. Its two stacked minor thirds distinguish it from major, minor and augmented triads.

Diminished Seventh Chords

A fully diminished seventh chord adds a diminished seventh above the root of a diminished triad. B–D–F–A-flat is B diminished seventh. B–D–F–A instead forms a half-diminished seventh chord.

How chords sound together

The term chord is often used to describe a group of three or more different notes played together at once. When you hear a chord, you’re hearing more than one note being played at once because multiple notes make up any single chord. Different combinations of notes make up different chords, so in that sense, chords sound differently depending on what combination of pitches you play at once. But music theory teaches us that certain combinations sound good together while others don’t.

Chord progressions

A chord progression is a sequence of chords. For example, I–IV–V–I in C major is C–F–G–C. A song may repeat one progression or use different progressions in its verses, chorus and bridge.