Semicolons
Use a semicolon to separate two related independent clauses (clauses that can stand as sentences on their own) that are not linked by a comma and coordinating conjunction (and, but, for, nor, or, yet, and so).
Jill did three hours of homework today; Jen did five-and-a-half.
Use a semicolon to separate two related independent clauses linked by an adverb (however, therefore, nevertheless, etc.).
My doctor told me to avoid heavy lifting; nevertheless, I helped Bill move the piano.
Use semicolons to separate items in a complex series.
A complex series contains internal punctuation. Semicolons help to clearly mark the break between each item in the series.
Today I met Linda, who is tall; Fred, who is a biology major; Amy, who likes to swim; and John, who has brown hair.
Do NOT use a semicolon between an independent and a dependent clause (one that cannot stand as a sentence on its own).
A comma is the appropriate punctuation between a dependent and independent clause.
WRONG: If you toss me the keys; I’ll open up the trunk.
RIGHT: If you toss me the keys, I’ll open up the trunk.
Semicolons go outside quotation marks.
Hank told me, “I don’t like cheese”; I think he’s crazy.
Colons
Use a colon to introduce a list.
The clause preceding the colon must be an independent clause. A colon should not separate parts of speech that naturally go together, such as an infinitive and its object (see below).
WRONG: My mother told me to buy: a box of crackers, a cake of soap, a package of toilet paper, a head of lettuce, and a sack of flour.
RIGHT: My mother told me to buy five things at the store: a box of crackers, a cake of soap, a package of toilet paper, a head of lettuce, and a sack of flour.
Use a colon to introduce an appositive (a phrase used to describe or define a noun).
Elsa had a thought: what if she walked around the mountain, instead of over it?
Use a colon to set off a second independent clause that modifies the first.
Aaron was happy today: he hopped and skipped all the way to the post office.
Use colons to introduce quotations after an independent clause.
Use a comma when introducing quotations after a dependent clause.
WRONG: Jodie said: “I think you are the coolest person I know.”
RIGHT: Jodie told me a secret: “I think you are the coolest person I know.”
Use colons in titles.
Procrastination: The Art of Wasting Time
Use colons in business letters and memoranda.
In business letters and memos, colons are used in salutations (Dear Mr. Soandso:) and in memo headings (To:, From:, Date:, Subject:, Dist:).
Use colons in numbers and addresses.
Colons are used for Biblical citations to separate chapter from verse (Mark 4:12), in clock times to separate hours from minutes (8:56 a.m.), in ratios (4:1), and in website addresses (http://www.sparknotes.com).
Dashes
A dash is typed as two hyphens. There should be no space between a dash and the words on either side.
Use dashes to highlight extra informational comments.
Helga’s strict rules—as well as her delicious schnitzel—are known for miles around.
Use dashes to set off important or surprising points.
Jonah just ate a million donuts—literally.
Use only one dash or pair of dashes per sentence.
WRONG: Sylvia—my favorite person—except for maybe Jed—in the whole world—is giving a tap dancing recital, and I am going to buy her flowers—I’m her best friend, you know.
RIGHT: Sylvia—one of my favorite people in the whole world—is giving a tap dancing recital, and I am going to buy her flowers, because I’m her best friend.
Reference: Strunk, Wiliam Jr., and E. B. White. The Elements of Style. 4th ed., Allyn and Bacon, 2000.
Copyright © 2009 Wheaton College Writing Center