Ooligan editors, per in-house style guide, always place a comma before the final item in a series of three or more items (typically preceding an and, an or, or a nor). This is called the Oxford comma or the serial comma. The Oxford comma has long been the subject of fierce and bloody debate among combatants in the usage wars.
Ooligan’s adoption of the Oxford comma is based on the recommendation of TheChicago Manual of Style—the style and usage Bible for non-journalistic writers (journalists follow the APStylebook suggestion to omit the serial comma, presumably to save space).
Oxford-haters say the serial comma is ugly and superfluous; most people outside of editors and academics don’t notice or care about the debated punctuation mark. So why should we use the Oxford comma, anyway? There are plenty of pro-comma arguments; take, for example, these humorous instances of ambiguity created by the lack of a serial comma: