What is a Chord?

A chord is what happens when you play two or more notes at the same time. That's it - just notes sounding together.

A chord combines notes so they sound at the same time. The simplest common chords use three notes, called triads; adding or changing notes changes the chord's interval structure and its role in the arrangement.

A single note vs. a chord

Tap the piano below to hear the notes individually and together. Then hit Play to hear three notes together: C, E, and G. Together, C, E, and G form a C major chord.

How chords are built

Many common chords are built by stacking notes in intervals of thirds. Start on a root note, skip one note in the scale, then skip another.

This root, third, fifth pattern is the starting point for a triad. Change the third or fifth and you change the chord quality; move one of the notes to another octave and you change the voicing without changing its name.

Major vs. minor

The difference between major and minor is one note: the third is lowered by a semitone. C major uses C-E-G; C minor uses C-Eb-G.

The third identifies the basic major or minor quality.

The third gives you a reliable way to identify major or minor quality in a basic triad. Instrument, register, voicing, and the surrounding progression also shape what you hear. The next lesson explores the two triad formulas in detail.

Why chords matter

Chords give a melody and bass line harmonic context. Their notes, register, rhythm, and voicing affect how much space the arrangement has and where the progression feels settled or unresolved.

Listen to some chords

Before tapping each one, predict whether it will sound major or minor from the chord name. Then listen for the third: it is the interval that distinguishes the basic major and minor qualities.