Serial comma

The serial comma (also referred to as the Oxford comma or Harvard comma) is a comma placed after the penultimate term in a list (just before the conjunction) when writing out three or more terms. For example, a list of three countries might be punctuated with the serial comma as "France, Italy, and Spain" or without it as "France, Italy and Spain". The serial comma can help avoid ambiguity in some situations, but can also create it in others. There is no universally accepted standard for its use. The serial comma is popular in formal writing (such as in academic, literary, and legal contexts) but is usually omitted in journalism as a way to save space. Its popularity in informal and semi-formal writing depends on the variety of English; it is usually excluded in British English, while in American English it is common and often considered mandatory outside journalism. Academic and legal style guides such as the APA style, The Chicago Manual of Style, Garner's Modern American Usage, Strunk and White's The Elements of Style, and the U.S. Government Printing Office Style Manual either recommend or require the serial comma, as does The Oxford Style Manual (hence the alternative name "Oxford comma"). Newspaper stylebooks such as the Associated Press Stylebook, The New York Times Style Book and The Canadian Press stylebook typically recommend against it. Most British style guides do not require it, with The Economist Style Guide noting most British writers use it only to avoid ambiguity. While many sources provide default recommendations on whether to use the serial comma as a matter of course, most also include exceptions for situations where it is necessary to avoid ambiguity or confusion (see Serial comma § Recommendations by style guides).