Somewhere along the line, someone discovered that if the this second movement were to be transposed from D major to G major, the entire piece could be played on a single G string on the violin and there comes the name Air on G String.
To bring further insult to JS Bach, Air on G String is normally played without any reference to its original composer nor his original intent.
Air on G String is an absolute lyrical piece and I would urge those that enjoy explore further by listening to the entire third orchestra suites in its original key in D major. There are only a total of 5 movements and it will be worth it.
Last but not least, I believe that G String panties which some would like to associate the piece Air on G String was furthest from JS BACH thought when he first composed it in D major. :)