It has long driven grammar nerds crazy.

And it has long driven grammar nerds crazy because even major language institutions can't agree on whether it should be used.Ironically, the Oxford comma is more common in the United States,where it's recommended by the MLA, the Chicago Style Manual,and the US Government Printing Office,though not by the AP Style Book.In the UK and other English-speaking countries,most style guides do not support the comma's use,with the exception of its namesake,the Oxford University Press.Why not use the serial comma?One of the main arguments is that the conjunction is usually enough to denote a separate entity.