There are two reasons that you would need to use this punctuation mark:
If you have a list (series of three or more) with commas already in it, upgrade to a semicolon to divide the items in the list. The semicolon provides a stronger separation between each of the items and aids reader clarity.
The guest list to my party features my boyfriend, Jake; Jen, my stylist; and my roommate, Julie.
Without the semicolons separating each individual, it could appear to someone who doesn’t know these three guests that you’re actually referring to six different people.
Joining Two Complete Thoughts
There are several ways to join two complete thoughts (meaning each thought has a subject and verb, and the thoughts could stand all on their own—otherwise known as “independent clauses”). One way to join those two complete thoughts (and avoid creating a run-on sentence) is to follow this formula:
|Complete Thought||+ semicolon||+ Complete Thought|
|He came to pick her up||;||however, she wasn't ready yet.|
|The parking lot was full||;||Marty looked for parking on the street.|
Use a hyphen to connect two or more descriptive words that act as a single unit (a.k.a. compound adjective).
The runny-nosed toddler sneezed all over me.
You wouldn’t just refer to the toddler as “runny” or as “nosed,” so you need to hyphenate the two words to create one descriptor.
The dash looks like two hyphens, and sometimes your computer will autocorrect them into one longer line (known as an m-dash). The main reason you would ever use dashes is to show emphasis.
Jules missed the beginning of the lecture—she’s always late.
The one catch with utilizing the colon is you must have a complete thought (a.k.a. “independent clause”) preceding the colon in order to receive the go-ahead from the Grammar Police to use it. Here are several reasons you would opt to use a colon:
Use a colon to introduce a list.
I have jeans in an array of colors: grey, dark blue, faded ebony, and maroon.
Use a colon to show emphasis.
There was one option: surrender was not in our game plan.
Use a colon to introduce a quote.
His response was always the same: “I should, but I won’t.”
Side Note: A common mistake writers make is to put a colon after the word “include” or “including.” Most often these are not complete thoughts, so they cannot end in a colon.
Incorrect: College majors include: biology, philosophy, and anthropology.
Use parentheses to deliver bonus information. Think of it this way: you are whispering to your reader the words that you place between parentheses.
Mary excels in math (especially calculus).
Here are a couple uses for quotes:
Use quotes when you are repeating what someone else said or wrote (they are a visual cue to your reader that those are somebody else’s ideas).
My girlfriend said, “It’s your turn to drive.”
You can also use quotes when referring to common phrases, slang, or jargon.
He used the word “like” way too much in his presentation.
Side Note: When typing, place punctuation like commas, periods, and question marks inside the quotation marks (like the examples above). The main exceptions are 1.) semicolons or 2.) when an actual quote is not a question but the complete sentence is (in which case the question mark is placed outside of the quotation marks).
Example: How many times is my mom going to say, “We can discuss it later”?
Italicizing and underlining mean the same thing; however, italics tend to be more modern, and the use of an underline leans a little more old school (this also varies by style guide). Just be sure that you use one or the other, and never use them at the same time.
Use italics or underlining around titles of newspapers, magazines, books, albums, TV shows, and films. (Note that this varies by style guide, so be sure to ask your instructor which style guide--MLA, APA, etc.--to use.)
There are two uses for apostrophes:
To show possession
I went to Michael’s house to study.
The three kittens’ mittens are hung up by the fireplace.
You’re going to do really well in this class.
The apostrophe in a contraction is a visual cue that a word was left out. In the above example, the apostrophe in “you’re” visually highlights that the word “are” has been removed for the sake of brevity.
Side Note: Contractions are typically considered to be casual. They are frowned upon in academic and formal writing.