Use commas to separate three or more words, phrases, or clauses written in a series or list.
Example: I drove home, cooked dinner, and got ready for the party.
In a list, the final comma before the conjunction is known as the “Oxford comma”, as in the phrase above: “cooked dinner, and got ready for the party.” This is an academically contentious comma. Some style guides and instructors will recommend going without, so the sentence in that case would read: “I drove home, cooked dinner and got ready for the party.”
Ultimately neither way is necessarily “incorrect”, and you as a writer are free to choose either! However, be consistent throughout your writing, and be sure to use your discretion about careful phrasing. As one author found out, there is a big difference between “I’d like to thank my parents, Ayn Rand and God” and “I’d like to thank my parents, Ayn Rand, and God.”
Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions (FANBOYS): for, and, nor, but, or, yet, so.
Example: He needed some cash, so he went to the ATM.
Use commas after introductory a) clauses, b) phrases, or c) words that come before the main clause.
Example: To be honest, I didn’t like the movie.
Example: According to the Bible, Joshua was the son of Nun.
