Chord (music)

A chord, in music, is any harmonic set of two or more notes (also called "pitches") that are heard as if sounding simultaneously. For many practical and theoretical purposes, chords are assumed to consist of three or more notes. These can be sounded simultaneously, but succession is also possible when implying the chord through arpeggiation.

Chords and sequences of chords are frequently used in Western, popular and traditional music. The most frequently encountered chords are triads, consisting of three distinct notes; these are built using superimposed intervals of thirds. For example, a C major triad contains the notes C, E, and G. More complex chords, such as seventh chords, ninth chords, and altered chords, include additional notes, creating richer and more varied harmonic textures.

The specific notes within a chord determine its quality (major, minor, augmented, diminished, etc.). Chord quality significantly affects the overall mood and character of a musical piece. Different inversions and voicings of the same chord can also subtly alter the sound and impact of the chord within a musical context.

Chord progressions are sequences of chords that form the harmonic foundation of a musical composition. The study and analysis of chord progressions are fundamental to understanding musical structure and harmony. Chord progressions provide a sense of movement and direction within a piece, and can create tension and release, contributing to the emotional impact of the music.

The function of a chord within a progression is also important. Chords are often categorized by their role in establishing or destabilizing a key or tonal center (tonic, dominant, subdominant, etc.). The relationship between chords and their functions within a key is essential to tonal harmony.