D major (or the key of D) is a major scale based on D, consisting of the pitches D, E, F♯, G, A, B, and C♯. Its key signature consists of two sharps. 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 appropriate for guitar music, with drop D tuning making two Ds available as open strings.

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.

DJ Tutor is the title given to Johnathan Lewis, and to the online community of DJs that he inspired through his Youtube channel "ellaskins".

Lewis' rough and ready, punk TV style^{[citation needed]} was a contrast to the slick image that DJs were presenting previously.^{[citation needed]}

His tutorial videos for beginners have started the careers of many professional DJs.

Thousands of new and experienced DJs have responded with videos and comments, so that DJ Tutor has become a social network for DJs from all over the world.^{[citation needed]} Lewis' catchphrase "Practise and N_Joy" has entered the DJ vocabulary.

Lewis grew up in Borth, near Aberystwyth, and still lives and works in West Wales.

He started working as a professional DJ in 1984.

Clubs and hotels he worked in include Starlight (New York), Tiffany's (Oslo) and the Continental Hotel (Isle of Man).^{[citation needed]} He also presented his own show "Phatbeats FM" on Radio Ceredigion, as well as running a mobile roadshow.

In September 2006 Lewis discovered Youtube, and started posting comedy videos, and drum tutorials.