Quite possibly you know this comma as the Oxford comma—because, we’re told, it’s traditionally favored by the editors at Oxford University Press. But as a patriotic American, and also because that attribution verges on urbane legendarianism, I’m loath to perpetuate that story. Or you may be familiar with the term “serial comma,” though for me “serial” evokes “killer,” so no again. Whatever you want to call it: Use it.