Conventions of Composition Rule 37

Rule: When using a series of three or more items (words, phrases, or subordinate clauses), you need a comma between each item and the next. If you use a final and or or, you can decide whether or not to include the comma preceding the and or or. [Note: this final comma is called the serial comma or Oxford comma, and grammarians debate its use to the death, almost not using hyperbole here. For a glimpse into this debate, look here or here, but any Google search will show you how seriously people take this topic.] If each element in the list is separated by and or or, you do not need commas. Where you hear a gap when you say the list aloud, put in a comma. [Remember that if the items in your list contain internal commas, you use semicolons to separate items on the list. See rule 3.]

Examples:

Correct: Kind, friendly, attractive people often love grammar.

Correct: Kind, friendly, and attractive people often love grammar.

Correct: Kind and friendly and attractive people often love grammar.

Practice deciding if and where these sentences need commas:

1. I studied German Greek and Chinese while at Hotchkiss.

2. The tall handsome trans man won our hearts minds and votes.

3. She told her wife she already looked under the table behind the shelves and in the cabinet.

Resources for further explanation of how to use commas in lists:

Getting it Right Serial Commas

UCL's The Ordering of Adjectives

Grammarly's Commas