, Modulation
Modulation is the process that a piece of music goes through
in order to change from one key centre to another key centre.
It is used to help give the music structure and variety. The
original key is called the home key; often, independent of how
many times the piece changes key, it will return to the home
key to end the piece.
The distance of the key change varies between composers
and eras, as does the length of stay in each key.
Modulation can occur through the use of a Pivot Chord.