Tonic (music)

The tonic is the first and most important note of a musical scale.

In western European tonal music of the 18th and 19th centuries, the tonic center was hierarchically the most important of all the different tone centers which a composer could use in a piece of music. There can be major scales and minor scales. The tonic remains the same in these two different "modes," for a given key, wheareas scale degrees such as the third degree and the sixth degree are altered in the minor scale.

The tonic plays an important part in determining why music composed in a minor scale sounds different from music composed in a major scale. The answer is not obvious, when one realises that each minor scale has the same key signature and hence same set of notes as a major scale. A minor scale and major scale with the same set of notes differ only in which one of these notes is the tonic. For example, C major and A minor have no sharps or flats.