A chord is multiple pitches sounded at the same time

A chord is a group of two or more pitches played simultaneously. This is the base definition underneath all harmony: whereas a melody or bassline is one pitch at a time, a chord stacks pitches so they sound together, and the resulting combination has a colour or quality (consonant, tense, bright, dark) determined by the intervals between the stacked notes. Chords are the harmonic material that basslines reinforce and that melodies are heard against. From this simple definition the course builds toward triads and progressions, but the atom-level fact — simultaneous pitches — is the discriminating idea that separates harmony from single-line playing.

Examples

On a keyboard, pressing C alone is a single note; pressing C, E and G together is a chord (a C major triad). Any set of pitches held at once is a chord.

Assessment

State what distinguishes a chord from a melody. Given audio or notation, decide whether what you hear is a chord or a single line, and justify by whether pitches sound simultaneously.