Punctuation is important. It may not come into play in spoken English, but the ability to use it correctly is one of the telltale signs of a skilled writer. Punctuation improves readability, helps emphasize specific points, and improves organization. It makes the page come alive, in a way.

Hyphens and dashes are among the most confusing and often misused punctuation marks of written English. In general terms:

• The hyphen (-) is used to join two or more words together.
• A dash (–), also known as an en dash, is used to separate a sentence into statements.
• An em dash (—) can take the place of commas, parentheses, or colons.

HYPHENS

Hyphens are used to join two related words, or parts of words, together in order to avoid confusion and add readability:

• Run-of-the-mill
• Up-to-date

Sometimes, a hyphen will be inserted to clarify a word containing letter collisions or when referring to family relations. There are also words whose hyphens appear for a time and then disappear. In some cases, a hyphen can completely change the meaning of a sentence:

• I re-sent that email VS I resent that email
• Twenty one dollar bills VS twenty-one dollar bills

Use a hyphen with numbers ranging from twenty-one to ninety-nine:

• Seventy-two
• Forty-eight

When writing fractions, place a hyphen between the numerator and denominator:

• Three-quarters
• Five-eighths

Use a hyphen when a number forms part of a compound:

• 100-meter dash (see what I did there?)
• 35-year-old man

DASHES

Dashes can be used to add statements or comments, as a more informal bracket. Dashes may be used to create emphasis in a sentence:

• You think that I’m strong – you’re wrong.
• They may end up together – you can never tell.

EM DASH

The em dash is probably the most versatile punctuation mark. It causes a different effect in every use, and can be used to replace commas, parentheses, and colons.

Many people confuse hyphens and dashes.

Replacing Commas

A pair of em dashes can be used instead of commas, to enhance readability. However, unlike commas, there are a lot more emphatic:

• When we finally were able to leave the elevator – three hours after it had shut down – we discovered the cheesecake had been eaten by the cat.

Replacing Parentheses

A pair of em dashes can replace a pair of parentheses. If you want to draw attention to the parenthetical content, use dashes. For more subtle text, consider parentheses.

When dashes are used instead of parentheses, the surrounding punctuation should be taken out:

• Upon finishing the hot dogs (all 22 of them), Billy sat down and wept.
  VS
• Upon finishing the hot dogs – all 22 of them – Billy sat down and wept.

When used at the end of a sentence, only a single dash is used:

• After three weeks on board, the crew was tired of the captain’s navigation (or, rather, lack thereof).
  VS
• After three weeks on board, the crew was tired of the captain’s navigation – or, rather, lack thereof.

Replacing Colons

The em dash can be used in place of a colon when you want to emphasize the conclusion of a sentence:

• After several long seconds, his face had already said it all – rancid cheesecake.

Multiple Usage

Two em dashes can be used to show missing letters of a word, whether unknown or intentionally omitted:

• B——, the defendant, had little to say.
• The letter only said: “F­­­——r yours, if you knew the r­­­——t horse, Mr. Blumenthal!”

When an entire word is missing, either two or three em dashes can be used. Surrounding punctuation should be placed as usual.

Spaces with the Em Dash

The em dash is typically used without spaces on either side, and that is the style used in this guide. Most newspapers, however, set the em dash off with a single space on each side.

Most newspapers — and all that follow AP style — insert a space before and after the em dash.