What is a Chord?

A chord is a combination of three or more notes sounding simultaneously to create harmony. Chords are the harmonic foundation of music, providing the backdrop for melodies and creating emotional texture.

When multiple notes sound together, they interact to create a collective sound that is greater than the sum of its parts. For example, playing C, E, and G together creates a C major chord—a sound that feels complete and resolved. This same collection of pitches is perceived differently than hearing them played in isolation.

CDEFGABCDEFGAB

C♯D♯F♯G♯A♯C♯D♯F♯G♯A♯

Chords serve several essential functions in music:

• Harmonic Support: They provide the underlying structure that melodies sit upon, much like a foundation supports a building.
• Emotional Expression: Different chord qualities evoke different feelings—major chords often sound bright and happy, while minor chords tend to sound darker and more introspective.
• Structural Framework: Chord progressions (sequences of chords) create patterns that help shape the form and narrative of a piece of music.

In contemporary music, chords don't always need to contain exactly three notes. Many modern compositions use two-note chords (called dyads) for texture and simplicity, while others stack four or more notes for greater complexity and richness. However, the traditional definition of three or more notes remains the foundation of chord theory.

Triads

Triads are three-note chords built by stacking intervals of thirds. Triads form the basis of most Western harmony and are the building blocks from which all other chord types are constructed.

A triad consists of three notes: the root, the third, and the fifth. These names refer to their positions in a scale—if you start on any note and count up through the scale (root = 1, second = 2, third = 3, etc.), the root is your starting point, the third is three scale degrees away, and the fifth is five scale degrees away.

When building triads, each note is stacked a third apart. In music, a third can be either major (spanning 4 semitones) or minor (spanning 3 semitones). The specific combination of major and minor intervals determines the chord quality:

Major Triads

Stacking a major third and then a minor third above creates a major triad. For example, C-E-G. This produces a bright, stable sound.

Minor Triads

Stacking a minor third and then a major third creates a minor triad. For example, A-C-E. This produces a darker, more introspective sound.

Diminished Triads

Two minor thirds stacked create a diminished triad. For example, B-D-F. This produces a tense, unstable sound that wants to resolve.

Augmented Triads

Two major thirds stacked create an augmented triad. For example, C-E-G#. This produces an ambiguous, open sound.

Triads are everywhere in music. Popular songs, classical symphonies, and jazz standards are all built using triads as the foundation of their harmonic structure. Understanding how triads work is essential for any musician looking to understand music theory and composition.

Chord Quality

Chord quality describes the specific combination of intervals in a chord and is determined by the intervals between the root note and the other notes. Major, minor, diminished, and augmented qualities each produce distinct sounds and functions within harmony. By changing just one or two notes, you can dramatically alter how a chord sounds and functions in a progression.

Major Quality

Major chords have a major third (4 semitones) above the root and a perfect fifth (7 semitones) above the root. They sound bright, stable, and resolved. Major chords are the most common chord type and form the basis of many happy, uplifting songs. Examples: C major (C-E-G), F major (F-A-C), G major (G-B-D).

Minor Quality

Minor chords have a minor third (3 semitones) above the root and a perfect fifth (7 semitones) above the root. They sound introspective, contemplative, or sad. Minor chords are equally common as major chords and are essential for expressing a wide range of emotions. Examples: A minor (A-C-E), E minor (E-G-B), D minor (D-F-A).

Diminished Quality

Diminished chords have a minor third and a diminished fifth (6 semitones). They sound tense, unstable, and unsettling. Diminished chords are often used as passing chords or to create tension that resolves to a more stable chord. Examples: B diminished (B-D-F), C diminished (C-Eb-Gb).

Augmented Quality

Augmented chords have a major third and an augmented fifth (8 semitones). They sound ambiguous, mysterious, and open-ended. Augmented chords are less common in traditional music but are frequently used in jazz and modern composition for their unique character. Examples: C augmented (C-E-G#), F augmented (F-A-C#).

Understanding chord quality allows you to choose the right chord for the emotion and function you want to achieve. A song can take on an entirely different character simply by changing a major chord to a minor chord, or by adding augmented or diminished chords for color and tension.

Seventh Chords

Seventh chords add a fourth note to triads, adding complexity and specific harmonic functions. Different seventh chord types create different levels of tension and resolution tendencies.

A seventh chord is built by adding a seventh note to a triad—that is, a note seven scale degrees above the root. This additional note can be either a major seventh (11 semitones above the root) or a minor seventh (10 semitones above the root), which creates different colors and harmonic functions.

Major Seventh Chords

Major triad plus a major seventh. These chords sound open, bright, and sophisticated. They are common in jazz and are often used as stable, resting chords. Example: C major 7th (C-E-G-B). This chord feels polished and resolved.

Dominant Seventh Chords

Major triad plus a minor seventh. These chords sound bluesy, funky, and unresolved. They create strong tension that naturally wants to resolve to a chord a perfect fourth away. For example, a G7 chord strongly resolves to C. This is one of the most powerful harmonic functions in music. Example: G7 (G-B-D-F).

Minor Seventh Chords

Minor triad plus a minor seventh. These chords sound dark, moody, and cool. They are frequently used in jazz, funk, and blues. Minor seventh chords are more stable than dominant sevenths but less resolved than major sevenths. Example: A minor 7th (A-C-E-G).

Minor Major Seventh Chords

Minor triad plus a major seventh. These chords have a unique, somewhat melancholic yet sophisticated character. They combine the darkness of a minor triad with the brightness of a major seventh. Example: C minor/major 7th (C-Eb-G-B). This chord is less common but very expressive.

Half-Diminished Seventh Chords

Diminished triad with a minor seventh. These chords sound tense and unresolved, often used in jazz to create instability. Example: B half-diminished 7th (B-D-F-A).

Diminished Seventh Chords

Diminished triad plus a diminished seventh (9 semitones). These chords sound extremely tense and are often used as passing chords or to create maximum tension. Example: C fully diminished 7th (C-Eb-Gb-Bbb).

Seventh chords are crucial for creating harmonic interest and movement in music. Understanding how they function and resolve is essential for composition, improvisation, and deeper music theory knowledge. Seventh chords are especially important in jazz and blues, where dominant sevenths and minor sevenths are used constantly to drive harmonic movement.