Semi-colons, Colons, and Dashes
Dashes
The first thing to know when talking about dashes is that they are almost never required by the laws of grammar and punctuation. Overusing dashes can break up the flow of your writing, making it choppy or even difficult to follow, so don't overdo it.
It's also important to distinguish between dashes and hyphens. Hyphens are shorter lines (-); they are most often used to show connections between words that are working as a unit (for example, you might see adjectives like "well-intentioned") or to spell certain words (like "e-mail").
With that background information in mind, let's take a look at some ways to put dashes to work in your writing.
1. To set off material for emphasis.
Think of dashes as the opposite of parentheses. Where parentheses indicate that the reader should put less emphasis on the enclosed material, dashes indicate that the reader should pay more attention to the material between the dashes. Dashes add drama – parentheses whisper. Dashes can be used for emphasis in several ways:
A single dash can emphasize material at the beginning or end of a sentence.
Example:
After eighty years of dreaming, the elderly man realized it was time to finally revisit the land of his youth – Ireland.
Example:
"The Office" – a harmless television program or a dangerously subversive guide to delinquency in the workplace?
Two dashes can emphasize material in the middle of a sentence. Some style and grammar guides even permit you to write a complete sentence within the dashes.
Example:
Everything I saw in my new neighborhood – from the graceful elm trees to the stately brick buildings – reminded me of my alma mater.
Example (complete sentence):
The students – they were each over the age of eighteen – lined up in the streets to vote for the presidential candidates.
Two dashes can emphasize a modifier. Words or phrases that describe a noun can be set off with dashes if you wish to emphasize them.
Example:
The fairgrounds – cold and wet in the October rain – were deserted.
Example:
Nettie – her chin held high – walked out into the storm.
2. To indicate sentence introductions or conclusions.
You can sometimes use a dash to help readers see that certain words are meant as an introduction or conclusion to your sentence.
Example:
Books, paper, pencils – many students lacked even the simplest tools for learning in nineteenth-century America.
Example:
To improve their health, Americans should critically examine the foods that they eat – fast food, fatty fried foods, junk food, and sugary snacks.
3. To mark "bonus phrases".
Phrases that add information or clarify but are not necessary to the meaning of a sentence are ordinarily set off with commas. But when the phrase itself already contains one or more commas, dashes can help readers understand the sentence.
Slightly confusing example with commas:
Even the simplest tasks, washing, dressing, and going to work, were nearly impossible after I broke my leg.
Better example with dashes:
Even the simplest tasks – washing, dressing, and going to work – were nearly impossible after I broke my leg.
4. To break up dialogue.
In written dialogue, if a speaker suddenly or abruptly stops speaking, hesitates in speech, or is cut off by another speaker, a dash can indicate the pause or interruption.
Example:
"I – I don't know what you're talking about", denied the politician.
Example:
Mimi began to explain herself, saying, "I was thinking – "
"I don't care what you were thinking", Rodolpho interrupted.