D – Re Major
In music theory, D major chord is built on D-F#-A notes by order: root – major third – minor third. This basic major chord has notes D-A-D-F# by order basses to trebles in the guitar.
This chord is derived from a major triad. Major triads may have a function as a dominant or subdominant degree beside tonic degree in harmony. In music theory, triads are built by three different notes. But in the guitar harmony, basic chords may be expanded by same kind notes that repeat themselves in different octaves.