Comma Rules

When should a comma be used? Learn about the rules of comma usage, along with examples of how to use commas in English sentences.

A comma is optional after a prepositional phrase that has fewer than five words, but you should always use a comma after a long prepositional phrase.

In American English, you should always place a comma or period inside the quotation marks. Learn more about whether to place the comma before or after quotation marks.

Unnecessary commas clutter up your writing and make your reader insert unnatural pauses. This affects the overall readability and clarity of your writing.

Use a comma before then when it connects two independent clauses or when it acts like an interjection. Put a comma after then when it acts as an interjection.

Where do you put commas in dates? In the American month–date–year format, a comma goes after the date. But in inverted style dates, you don't need a comma.

A comma splice occurs when you combine two independent clauses with only a comma. Learn more about how to fix a comma splice in this article.

Use a comma before "such as" if it's part of a nonrestrictive clause. Learn more in this article.

You need a comma after "thank you" if you're thanking someone directly or if it's the last part of a letter or email before your sign-off. We break down the rules and give examples in this post.

Should you use a comma before or after parenthesis? Generally, you should only use a comma outside a closing parenthesis, though there are some exceptions to this rule.

Do you know when you should use a comma before that? In this article, we’ll show you how to correctly use a comma before that, and give you examples of its proper usage.

When do you put a comma before and in a sentence? Use a comma before and when joining two independent clauses or in a list of three or more items.

Do you put a comma before which in a sentence? If it is part of a non-restrictive clause, you should use a comma before which.

This article will show you when to use a comma before because in your writing. You normally don’t need a comma, but there are a few exceptions.

Use a comma before or when it connects two independent clauses. You can also use a comma before or if it appears in a list. This is called an Oxford comma.

Use a comma before except when it acts as a coordinating conjunction or subordinating conjunction, or when it begins a parenthetical phrase. Learn more here.

Use a comma before so when it’s acting as a coordinating conjunction to connect independent clauses. Use a comma before and after so when it’s acting as a filler word.

Use a comma before as well as when the following information is extra information. Do not use a comma when both clauses are equally important.

You should only use a comma before including when the word is introducing a nonessential clause. Learn more about this grammatical rule.

Use a comma before but when it connects two independent clauses. Use a comma after but when it functions as an interjection.

Comma punctuation is one of the hardest types of punctuation to master. Here are ten rules on when to use commas in sentences, lists, dates, and more.

Use a comma before which, where, and who when the following information is non-essential. Do not use a comma before a relative pronoun when the information is essential.

Do you need to add a comma before or after the word "however"? It depends on the situation. Learn the rules for punctuating a sentence with "however" in this post.

Using the Oxford comma is very important. Seriously. Find out why!