C-D Major is a musical scale that consists of two major chords: C Major and D Major. The C Major chord is made up of the notes C, E, and G, while the D Major chord includes D, F#, and A. These chords are often used in various musical genres, providing a bright and uplifting sound. In the context of music theory, C-D Major can be seen as a progression that moves from one key to another. This transition creates a sense of movement and can enhance the emotional impact of a piece. Musicians frequently use this progression in compositions and improvisations.