Two of the most misused and abused punctuation marks in the English language are colons and semicolons. They each have specific functions and cannot be used interchangeably. To help cut through the confusion, remember these simple rules:
• Semicolons replace commas in a list whose items themselves contain commas. For example:
Liz tried several things to treat her allergies: taking over-the-counter medications such as Chlor Trimeton, Zyrtec, and Claritin; alternating those drugs; wearing mosquito netting over her head; and, finally, swearing never to go outside in the spring.
• Use a semicolon—not a comma—to separate independent clauses that don’t have coordinating conjunctions (and, but, or). For example:
Yes, I see the mess you’ve made; you’ll be cleaning it up tomorrow.
• Use a semicolon between main clauses joined by a conjunctive verb (however, therefore, then). For example:
“However” is not a coordinating conjunction; therefore, it cannot be used by itself to link two clauses.
• Do not use a semicolon to separate an independent clause from a clause dependent on it. Use a comma instead. For example:
Their inane, vacuous chatter made it difficult to concentrate, especially because she was trying to write.
(An incorrect example would be: Their inane, vacuous chatter made it difficult to concentrate; especially because she was trying to write.)
• A colon may be used after an independent clause to introduce a list of items.
The steps are as follows: Turn on your computer, stare at the blank screen, and wait to be inspired. (Capitalize the first letter of a complete sentence that follows a colon; otherwise, lowercase the first letter—unless it begins a proper name, of course.)
• Do not use a colon if the sentence is continuous without it. For example:
To be a great writer you need curiosity, tenacity, and a sense of humor.
(An incorrect example would be: To be a great writer you need: curiosity, tenacity, and a sense of humor.)
• A colon may also be used to emphasize a word, phrase, clause, or sentence that amplifies or explains the first. For example:
I can think of only one alternative: bank robbery.
• Use a colon to introduce a quotation of two or more sentences. For example:
Bertrand Russell once said: “Science is what you know. Philosophy is what you don’t know.”
Unlike the rules for hyphens and commas, the rules for semicolons and colons are fairly straightforward. Semicolons separate things. Colons introduce or define things. Just remember to use them wisely.
Laura Hale Brockway blogs at impertinentremarks.com.