In musical harmony, an inversion is the change in position of the notes in a chord so that a different chord note becomes the bass note. For example, a “C Major triad” is spelled C – E – G in root position (C, the root, is the lowest pitch); in first inversion the third (E) is the lowest note, with the chord spelled E – G – C. In second inversion, the fifth (G) is the lowest voice and the chord is spelled G – C – E. The different forms that a chord may take by changing inversions can affect the sound of the chord and are often used to smoothly lead from one chord to the next.
Inversions may also be used in melody. Melodic inversion is an exchange of ascending and descending movement, so the ascending interval C up to F (up a fourth), in descending becomes C down to G (down a fourth).