A Chord is a set of three or more different musical notes played at the same time.

It is the fundamental building block of harmony in music. The specific combination of notes (the intervals between them) is what defines the quality and emotion of the chord, such as major, minor, diminished, etc.

For example, the C major chord is formed by the combination of the notes C, E, and G. When played together, they create the characteristic sound of a major chord.