The serial comma (also known as the Oxford comma or Harvard comma, and sometimes referred to as the series comma) is the comma used immediately before a coordinating conjunction (usually and or or, and sometimes nor) preceding the final item in a list of three or more items. For example, a list of three countries can be punctuated as either “Portugal, Spain, and France” (with the serial comma) or as “Portugal, Spain and France” (without the serial comma).
Opinions vary among writers and editors on the usage or avoidance of the serial comma. In American English, the serial comma is standard usage in non-journalistic writing that follows the Chicago Manual of Style. Journalists, however, usually follow the AP Stylebook, which advises against it. It is used less often in British English, where it is standard usage to leave it out, with some notable exceptions such as Fowler’s Modern English Usage. In many languages (e.g., French, German, Danish, Italian, Polish, Spanish, Greek ) the serial comma is not the norm and may even go against punctuation rules. It may be recommended in many cases, however, to avoid ambiguity or to aid prosody.
Arguments for and against
Common arguments for consistent use of the serial comma:
- Use of the comma is consistent with conventional practice.
- It matches the spoken cadence of sentences better.
- It can resolve ambiguity (see examples below).
- Its use is consistent with other means of separating items in a list (for example, when semicolons are used to separate items, a semicolon is consistently included before the last item, even when and or or is present).
Common arguments against consistent use of the serial comma:
- Use of the comma is inconsistent with conventional practice.
- The comma may introduce ambiguity (see examples below).
- It is redundant in a simple list, because the and or the or is often meant to serve (by itself) to mark the logical separation between the final two items, unless, of course, the final two items are not truly separate items but are two parts of a compound single item.
- Where space is at a premium, the comma adds unnecessary bulk to the text.
Many sources are against both systematic use and systematic avoidance of the serial comma, making recommendations in a more nuanced way (see Usage and subsequent sections).
Hat tip to Glenn Reynolds on Facebook for the cartoon.
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