Diatonic harmony is based on pitches that are found in the key of a composition, without accidentals. In a major key there are seven pitches, and in a minor key the raised 6th and 7th scale degrees in the ascending melodic minor form are considered within the key. In tonal music this form of minor is used in all parts. Chromatic harmony differs from diatonic because accidentals are employed to create non-diatonic chords. The reason for most of these accidentals is explained by their theoretical function. The following lessons address these functions:
Chromatic harmonies are used to expand the palette of pitches, adding fresh colors and pivoting to new key areas. Often, the presence of a sharp or flat is a clue to the type of chromatic chord you see and hear. In each lesson, the clues provided by chromatic inflections are explained. Often these altered chords lead to a Modulation, or change of key.