When interrupting the sentence flow, use a comma before and after the expression "after all" in the middle of a sentence. At the start of a sentence, "after all" must be followed by a comma when meaning "despite that" or "because".

Expressions and words that interrupt the sentence flow, like however, nevetherless, or though, must be surrounded by commas in mid-sentence.

Add a comma after the words well, why, hello, and hey to introduce a new sentence. Alternatively, you can use an exclamation mark to show emphasis, emotion, or surprise. An exclamation mark after these introductory words replaces a comma.

Place a comma before "including" when introducing an example (or a series of examples) to illustrate what has been recently said.

Use a comma before and after for example and for instance in the middle of a sentence. Replace the first comma by a semicolon to introduce a complete sentence with these expressions.

Place a comma before and after namely, that is, and specifically to introduce a list of items or include information that clarifies the meaning of a sentence.

We separate the different elements of a location (street address, city, and state) with commas.

Do not place a comma between the month and the day of the month; they are considered a single unit in English. Add a comma after the day of the week, the day of the month, and the year.

We add a comma after the introductory words "yes" and "no" at the start of a sentence.