Writing Center

Northern State University

Commas and Apostrophes

Commas and apostrophes can be confusing, but the following guidelines should help you understand them more clearly.

When to use commas:

1.  Use commas to separate three or more items in a list.  If you have only two items in your list, you don’t need commas.  Example: He hit the ball, dropped the bat, and ran to first base.  The three items in your list are “hit the ball, dropped the bat, and ran to first base.”  The comma before the “and” is optional--just be consistent in your usage.

2.  Use a comma and a connecting word (and, but, or, so, yet) to join two complete sentences.  The comma is placed before the connecting word, not after it.  Also, remember that a comma can’t be used to join two sentences unless the connecting word is present. Example: He wanted to come with us, but he was too busy.

3.  Use a comma after an introductory element that starts with an “ing” word. In these situations, the comma is often placed right before the subject of the sentence.  If you’re not sure where to put a comma in these situations, ask yourself how many words in the opening portion of the sentence could be eliminated without creating a fragment (incomplete sentence).  Put the comma after the last word that could be eliminated. Example: Running to catch the bus, I tripped and fell.  (“Running to catch the bus” could be eliminated without creating a fragment.)

4.  Use a comma after an introductory element that starts with a “signal word” indicating time or condition (after, when, during, as, if, even though, because, in addition, however, therefore). In these situations, the comma is often placed before the subject of the sentence.  If you’re not sure where to put a comma in these situations, ask yourself how many words in the opening portion of the sentence could be eliminated without creating a fragment (incomplete sentence).  Put the comma after the last word that could be eliminated. Examples: Because he wasn’t feeling well, he decided to go to the doctor.  However, he couldn’t get an appointment.  (“Because he wasn’t feeling well” and “However” could both be eliminated without creating a fragment.)

5.  Use commas before and after any “added information” in the middle of a sentence. This “added information” is not absolutely necessary to the meaning of the sentence, and it sometimes describes something in the sentence.  In addition, it is usually placed between the subject and the verb. Examples: Her sister, who is taking classes at Northern, is also going on the trip.  Personification, a form of figurative language, is used several times throughout this poem.

Note: If you add information in the middle of a sentence, use either two commas to set it off or none. In other words, never use only one comma between a subject and a verb.

6.  Use a comma to separate describing words (adjectives) if they can be joined by “and” or are roughly equal (in other words, they can be switched around without affecting the sentence). Think of the tall, handsome man and the little old lady when you’re trying to decide if you need a comma in these situations.  You could say “He is a tall and handsome man.”  However, you would not say “She is a little and old lady.”  The comma takes the place of the “and.”  If the “and” doesn’t work in the sentence, you don’t need the comma.  Example: They toured an old, abandoned mine.  (You could say “The mine was old and abandoned.”)

7.  Use a comma before a quote.  This is especially important when writing research papers.   Example: Smith writes, “Some people do not know how to use sources effectively.”

8.  Use a comma before a phrase that expresses a contrast.  Phrases that express contrast often begin with the word “not.” Examples: They bought the red car, not the blue one.  She wanted to take the history class, not the math class.

9.  Use a comma to avoid confusion in a sentence.  This relates to guidelines 3 and 4.  Examples:  For most, the class is very important.  Outside, the street was swarming with activity.

10. When dates and years are used together in a sentence, use a comma to separate the date from the year and the year from the rest of the sentence.  If the date or year is used by itself, no commas are needed.  Examples: October 15, 1975, is the date my sister was born.  October 15 is my sister’s birthday.  (No comma needed)

When to use apostrophes:

You do not use an apostrophe to make something plural.  Instead, you use an apostrophe to show possession.

1.  Use an apostrophe to show individual possession. In other words, use an apostrophe to show that one person or thing “owns” something else. Examples: Maria’s book, the dog’s tail, South Dakota’s weather, NSU’s football program, Tom’s and Mary’s test results (two different scores).

2.  Use an apostrophe to show joint possession. In other words, use an apostrophe to show that two or more individuals “own” something together--it belongs to both/all of them.  You probably won’t use this construction very often.  Examples: Paul and Jami’s car, Tom, John, and Steve’s room.  Notice that the apostrophe and the “s” are added only to the last name in the list.

3.  Use an apostrophe to show plural possession. In other words, use an apostrophe to show that a group of people or things “owns” something.  In these situations, the word showing possession usually ends in “s,” and the apostrophe is placed after this final “s.”  Examples: the managers’ meeting (a meeting for all the managers), the students’ lounge (the lounge belongs to all the students), the students’ books (the books belong to the students).

Note: If a word does not use an “s” to form its plural (man, child, woman), you must add both an apostrophe and an “s” to show possession.  The apostrophe will be placed before the “s.”  Examples: men’s clothing department, children’s books, women’s rights.

4.  If a singular word ends in “s,” you can show possession by adding either an apostrophe alone or by adding an apostrophe and an “s.”  Example: If you wanted to talk about the songs of Garth Brooks, you could say “Garth Brooks’ songs” or “Garth Brooks’s songs.”  Either version would be correct.  Just be consistent in your usage--pick a method and stick with it!

5.  Do not use an apostrophe to make the following words show possession: your, it, her, our, who, their. These words show possession by adding only an “s.”  Examples: yours, its, hers, ours, whose, theirs.

Note:  “It’s” does not show possession!  It is a contraction of “it is.”  If you’re unsure which word to use (“it’s” or “its”), substitute “it is” in the sentence.  If “it is” sounds correct, you want the apostrophe.  If “it is” sounds strange, you do not want the apostrophe.