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.
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).
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.