Chord
A chord is several notes sounding at the same time. The most common chord is the triad: three notes stacked in thirds, such as C–E–G.
One note after another is a melody; three or more together make a chord. On the staff the notes of a chord are written one above the other and played together. A triad looks like a snowman: three notes on three lines in a row, or in three spaces in a row.
A chord is named by the note it is built on, its root: C is C–E–G, F is F–A–C, G is G–B–D. These chord letters stand above the melody in songbooks. A plain letter means a major triad, a small m a minor one (Am is A–C–E), and a 7 adds a fourth note (G7 is G–B–D–F).
Chords are the basis of accompaniment: the right hand plays the melody, the left hand the chords. The three main chords of C major – C, F and G (tonic, subdominant, dominant) – carry hundreds of songs. The same notes of a chord can be stacked in another order: that is an inversion.
What it sounds like
A single note sounds thin; a chord sounds full and rich. A major chord sounds bright, a minor one darker, and a dominant seventh tense, waiting for the tonic.
Where it is taught: the studio’s interactive textbook, chapter 9, “Triads: C, F, G”.