One of the earliest comma rules students are taught is to use commas in a list of three or more ideas. The rule is straight forward, use commas to separate three or more items, phrases or clauses written in a series. Still, it causes confusion; Students often ask, “Should I use the Oxford comma, or not?” The answer is not straightforward, because it depends.
The Oxford comma is the last comma used in a series of three or more items, often before ‘and’ or ‘or.’
- My mother brought home tea, coffee, and water.
- I had to complete an application, interview, and submit my transcript when applying to medical school.
In these examples, the Oxford comma is after ‘coffee’ and ‘interview.’ In many cases, using the Oxford comma is necessary and provides clarity in your communication.
The Oxford comma is considered grammatically optional. Some style guides, like the Chicago Manual of Style, require you to use it, while others, like the Associated Press Stylebook, consider it unnecessary. The Pulse and University editorial style guide follow AP Style and ask that the Oxford comma is not included when writing articles for The Pulse, web or other public-facing communications. However, in APA and NLM, it is generally considered necessary.
In English writing, the rule, use commas to separate three or more items, phrases or clauses written in a series, is generally accepted. That said, writing is rhetorical, and it is essential that writers identify their audience when writing and give them what they require when considering the Oxford comma.
[Editor's note: the Oxford was removed from this article except where usage examples were shared]