Modulation (music)

In music, modulation is the change from one tonality (either a tonic or a mode, or both) to another. This may or may not be accompanied by a change in key signature (a key change). Modulations articulate or create the structure or form of many pieces, as well as add interest. Treatment of a non-tonic chord as a temporary tonic, for less than a phrase, is considered tonicization.

Modulation is the essential part of the art. Without it there is little music, for a piece derives its true beauty not from the large number of fixed modes which it embraces but rather from the subtle fabric of its modulation.