When should a comma be used in a sentence?

Commas are one of the most frustrating grammatical concepts, even for native English speakers. Nevertheless, there are specific rules for when you should and shouldn't use commas. Building our grammar checker we've identified 26 places where you might need a comma, including everything from appositive phrases to items in a list. In this article, I will explain all of these places along with examples of how to use commas in English sentences.

So, where do commas go in a sentence? This is the definitive list:

• Before a coordinating conjunction when it separates two independent clauses.

• Before "then" when it separates two independent clauses.

• Before a coordinating conjunction when it separates an independent and dependent clause as an Oxford comma.

• After an initial/introductory adverb that modifies a whole sentence or independent clause.

• After a time phrase that comes before a sentence or independent clause.

• After a subordinate clause—one that starts with a subordinating conjunction.

• Before a subordinate clause—in some specific cases.

• Between two adjectives when they both modify the noun—coordinate adjectives.

• After an introductory prepositional phrase.

• Before and after a participle phrase.

• When a word is omitted intentionally for stylistic reasons.

• After an adverbial infinitive phrase.

• At the end of a quotation, before the closing quotation mark.

• Before an opening quotation mark.

• To set off contrasting phrases.

• Before an appositive.

• After an appositive.

• Before "which" in nonrestrictive phrases.

• To separate list items.

• To separate out a parenthetical element of a sentence.

• To separate city and country/city and state.

• To set off a vocative.

• To separate the day from the month, and the date from the year.

• Before and after "too."

• In numbers as a separator.

• Before and after “please.”