D major (or the key of D) is a major scale based on D, consisting of the pitches D, E, , and G, A, B, and . Its key signature consists of two sharps (see below: Scales and keys). Its relative minor is B minor and its parallel minor is D minor.
D major is well-suited to violin music because of the structure of the instrument, which is tuned G D A E. The open strings resonate sympathetically with the D string, producing a sound that is especially brilliant.
It is thus no coincidence that many classical composers throughout the centuries have chosen to write violin concertos in D major, including those by Mozart (No. 2, 1775, No. 4, 1775); Ludwig van Beethoven (1806); Paganini (No. 1, 1817); Brahms (1878); Tchaikovsky (1878); Prokofiev (No. 1, 1917); Stravinsky (1931); and Korngold (1945).
It is also appropriate for guitar music, with drop D tuning making two Ds available as open strings. Domenico Scarlatti often imitated the mannerisms of the guitar in his keyboard sonatas, and this might be the reason that more than 70 of his 555 sonatas are in D major; more than any other key.
For some beginning wind instrument students, however, D major is not a very suitable key, since it transposes to E major on B-flat wind instruments, and beginning methods generally tend to avoid keys with more than three sharps.
Even so, the clarinet in B-flat is still often used for music in D major, and is perhaps the sharpest key that is practical for the instrument. There are composers however who, in writing a piece in D minor with B-flat clarinets, will have them change to clarinets in A if the music switches to D major.
The vast majority of tin whistles are in D, since they are often used in music with fiddles.
In the baroque period, D major was regarded as "the key of glory", hence a lot of trumpet concertos were in D major, such as those by Fasch, Gross, Molter (No. 2), Leopold Mozart, Telemann (No. 2), and Giuseppe Torelli. Many trumpet sonatas were in D major, too, such as those by Corelli, Franceschini, Purcell, Torelli, etc. With the invention of the valve trumpet, however, preference shifted to the flatter keys, and thus Haydn wrote his famous trumpet concerto in the key of E-flat major. "The Trumpet Shall Sound" and the "Hallelujah" chorus from Handel's Messiah are also in D major.
23 of Haydn's 104 symphonies are in D major, making it the most often used main key of his symphonies. The vast majority of Mozart's unnumbered symphonies are in D major, namely K. 66c, 81/73, 97/73m, 95/73n, 120/111a and 161/163/141a.
Scriabin considered D major to be golden in color and, in a discussion with Rimsky-Korsakov, he gave an example from one of his own operas where a character sang in D major about gold.
