What is a Chord?

A chord is three or more notes played simultaneously. The most fundamental chord type is a triad — three notes stacked in thirds. Every triad has a root (the note that names the chord), a third (which determines major or minor quality), and a fifth (which provides stability).

For example, a C major triad consists of C (the root), E (a major third above C), and G (a perfect fifth above C). Play these three notes together on a piano or guitar and you hear the bright, open sound of C major. Change the E to E♭ and you get C minor — a darker, more introspective sound from a single note change.

Triads are the building blocks of all harmony in Western music. Seventh chords add a fourth note, extended chords add fifths and beyond, but every chord traces back to the triad. Understanding this foundation unlocks the entire chord vocabulary.