D major is a musical key that is based on the note D. It consists of two sharps: F# and C#. This key is often associated with a bright and cheerful sound, making it popular in various music genres, including classical, pop, and folk. In terms of scale, the D major scale includes the notes D, E, F#, G, A, B, and C#. Musicians often use this key for compositions and performances, as it is relatively easy to play on many instruments, such as the guitar and piano.