top of page

Crash course in punctuation

Period [.]
1. Use a period to show the end of a sentence.
Gator football is a popular sport in Tallahassee.

2. Use a period after certain abbreviations.
It is 4 p.m. in Pittsburgh right now.
Note: AP style is to punctuate times without “:00” after the number: 4 p.m., not 4:00 p.m. When you use the month and day, abbreviate longer months (Jan., Feb., Aug., Sept., Oct., Nov. and Dec.), and use only the number, not “-nd” or “-st” or “-th” after the number: Sept. 1, not September 1st. It’s a good idea to include the day of the week too: Monday, April 8.


Question Mark [?] and Exclamation Mark [!]
1. Use a question mark at the end of a sentence to show a direct question.
How many Carnegie Mellon students does it take to screw in a light bulb?

2. Use an exclamation mark at the end of a sentence to show surprise or excitement.
We won the national championship!


Comma [,]
1. Use a comma to show a pause in a sentence.
Therefore, not everyone will be attending.

2. Use a comma with quotation marks to show what someone has said directly.
“I could tell you how I did it,” she said, “but then I’d have to kill you.”

3. Use commas for listing three or more items.
Thank you for your support of our faculty, staff and students.
Note: AP style is to punctuate serial commas as A, B and C, not A, B, and C. Other styles differ. Chose one and be consistent.

4. Use commas around relative clauses that add extra information to a sentence.
Patricia, who is the vice president’s administrative assistant, is widely known for her patience and diplomacy.

Apostrophe [‘]
1. Use an apostrophe to show ownership of something. For nouns in plural form, put the apostrophe at the end of the noun.
Examples: These are the professor’s books. (books that belong to the professor)
These are the professors’ books. (books that belong to professors)

2. Add apostrophe plus s (’s) to form the possessive of singular words except when
pronunciation would be difficult. Then, put an apostrophe at the end of the word (s’).

the car of Ms. Jones = Ms. Jones’s car
the dial on a phone = a phone’s dial
a vacation of one week = a week’s vacation
Exceptions: Jesus’ teachings, Charles’ xylophones

3. Use an apostrophe to show letters that have been left out of a word.
Note: Do not use apostrophes to show plural – “Ham’s are on sale today” or “The Smith’s live here.” The Smith family = The Smiths. Their house is the Smiths’ house. But Mr. Meyers and his family are the Meyerses, which sounds awkward. Best to go with the Meyers family. (Ask me how I know.)


Quotation Marks [“ ”]
1. Use quotation marks to show what someone has said directly.
Examples: Pee Wee Herman said, “If you love fruit salad so much, why don’t you marry it?”
“I thought I had mono once,” Garth said, “but it turns out I was just bored.”
Note: Be careful not to “overuse” quotation marks. They do not “add” emphasis. They only “distract” from readability.


Colon [:]
1. Use a colon to introduce a list of things after a complete sentence.
Correct: George Foreman has five sons: George, George, George, George and George.
Incorrect: George Foreman’s five sons are: George, George, George, George and George.

2. Use a colon to introduce a long quotation.
Barney has been known to sing this song: “I love you. You love me. We’re a happy family.”


Semicolon [;]
1. Use a semicolon to join related sentences.
Homecoming is one of my favorite events; I just love it when they crown the queen.

2. Use a semicolon in lists that already have commas.
Our children are Ryan, 25; John, 20; Melody, 13; and Merry Glynn, 11.

Dash [–]
1. Use a dash before a phrase that summarizes the idea of a sentence.
Kind, gentle and loving – that is how I’d describe my dogs.

2. Use a dash before and after a phrase or list that adds extra information in the middle of a sentence.
He will come back – I promise you this – but not until you refill the freezer with ice cream.


Hyphen [-]
1. Use a hyphen to join two words that form one idea.
Blue-eyed boy, fire-resistant toy

Note: do not hyphenate such phrases if they come AFTER the noun.
She is a long-legged girl. But… The girl is long legged.
I want an up-to-date report. This report is up to date.
The three-year-old house fell apart. The house is three years old.

2. Use a hyphen to join prefixes to words. A dash separates, a hyphen connects.
Examples: anti-American, non-contact sport
Note: Typographically, a dash is called an “em dash” and is made up of two hyphens, two “en dashes,” just like the letter “m” looks like “n” plus “n.”


Parentheses and Brackets [ ] ( )
1. Use brackets when you need to include a phrase within them that uses parentheses.
This situation happens mostly in scientific writing or references/citations. If you need them in regular prose, and things are that complicated, you probably need to rewrite your sentence.

2. Use parentheses to enclose words or figures that clarify or are used as an aside.
Examples: Please pay me five hundred dollars ($500). She sat down (after realizing her dress was ripped) and lost her balance on the chair.

Note: AP style discourages using parentheses to reference an abbreviation immediately after the full name – for instance, American Bottle Club (ABC). Oddly, some writes use the abbreviation then never refer to the entity again in their article. Usually readers are smart enough to figure out what the abbreviation is after you’ve named the entity, but this issue is a style preference. If you like it, leave it in. If you don’t, leave it out.

Also, parentheses slow down a reader, so if you don’t need them, don’t use them. The second example could have just as easily have used commas.

bottom of page