Three or More Items = Commas
Series commas are also known as Oxford commas, and they appear in series of items when there are three or more items. This comma is more optional in British English, but more commonly used in American English. The trick is to be consistent: if you choose to use the series comma, do so consistently. Basically, this rule states that a comma has to be placed after every item in a list of three or more items. These items may consist of words, phrases, or clauses. The words and phrases are usually easy to see. It’s long-winded sentence with multiple clauses that can be difficult to sort out.
Look at these examples:
- Deciduous fruits like apples, peaches, and pears grow best in temperate climates.
A list of words. Simple.
- In order to write a coherent essay, one should choose a topic, do research, and write the essay.
A list of verb phrases. Still fairly simple.
- The prosecutor argued that the defendant, who was at the scene of the crime, who had a strong revenge motive, and who had access to the murder weapon was guilty of homicide.
Less simple because of the list of clauses. Clauses are longer and more confusing. But simple if you can find the clauses and not be tempted to add a comma after “weapon.”
Tip: Some writers choose to omit the last comma that precedes the coordinate conjunction. However, that can sometimes create ambiguous sentences, so it’s best to use at all times, but as I warned above, be consistent.
Ready to test your eye with some exercises?