What is a chord?

A chord is a set of two or more pitches, usually played simultaneously or in quick succession.

In Western music, the most "basic" or "common" type of chord is a triad. Triads contain three pitches and are most commonly major or minor. Other types of triad include augmented, diminished, and suspended.

Diatonic chords

Diatonic refers to notes and chords that belong in a certain key.

For example, in C major:

• The note F is diatonic because it is part of the key

• The note F# is non-diatonic or chromatic because it does not belong to the key

The same applies to chords. In C major:

• The chord Dm (D F A) is diatonic because all three notes are part of the key

• The chord D (D F# A) is non-diatonic because there is one or more notes that do not belong to the key

Major keys

Musicologists often use Roman numerals to describe the position/function of chords in a key.

Using C major as an example:

• Chord I (C E F) is Major

• Chord ii (D F A) is Minor

• Chord iii (E G B) is Minor

• Chord IV (F A C) is Major

• Chord V (G B D) is Major

• Chord vi (A C E) is Minor

• Chord viiº (B D F) is Diminished