A little music from one of the most prolific composers of all time. Bach didn't really invent any new forms of music but perfected the classical forms and set the benchmark for classical compositions.
Air on a G-string is from his 3rd orchestral suite in D major and it is played here by the RFCM symphony orchestra.
One of the more plausible reasons why it is called Air on a G-string comes via Wiki:
The title comes from violinist August Wilhelmj's late 19th century arrangement of the piece for violin and piano. By transposing the key of the piece from its original D major to C major and transposing the melody down an octave, Wilhelmj was able to play the piece on only one string of his violin, the G string.
Later, a spurious story was put about that the melody was always intended to be played on the G string alone.