Commas: Items in Series (The Serial Comma) Thankfully, the serial comma has nothing to do with breakfast foods or notorious killers. This comma is the one that should be placed between items in a series to signal to the reader that each item on the list is separate. However, controversy rages (mainly in writing courses) over when a comma should and should not be used before the last item of the list. This lesson solves this faux controversy by pointing out that different styles of writing (and the style guides which support them) call for different practices. If you experience difficulty in playing the video below, copy and paste this URL into a new browser window: http://polaris.umuc.edu/ewc/web/serial_comma/serial_comma.htm