The serial comma, or Oxford comma, is the comma used before a conjunction introducing the final item in a list or series. News style guides, The AP Stylebook and The New York Times Manual of Style and Usage, generally omit the serial comma, and the Publication Manual of the APA, The Chicago Manual of Style, and the MLA Style Manual require it.
Cars, trucks, and vans
He eats, sleeps, and writes.
There are three XHTML document types: transitional, strict, and frameset.
Cars, trucks and vans
He eats, sleeps and writes.
There are three XHTML document types: transitional, strict and frameset.
Note: The AP Stylebook and The New York Times Manual of Style and Usage include the serial comma in cases where its omission would result in potential confusion. Sometimes this comma’s absence necessitates different surrounding punctuation.