Dashes and hyphens

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Dashes and hyphens aren’t interchangeable. Follow these guidelines to help you use them the right way and in the right places.

Em dashes

Use to set off or emphasize parenthetical phrases.

  • Use an em dash (—) to set off a parenthetical phrase with more emphasis than parentheses provide. Don’t add spaces around an em dash.
  • Use one em dash on each side of a phrase embedded in a sentence.

Example:

The information in your spreadsheet—numbers, formulas, and text—is stored in cells.

  • Use one em dash to set off a phrase at the end of a sentence.

Example:

If you’re not sure about the details, look at the illustrations in the wizard—they can help you figure out what type of connection you’re using.

Don’t use an em dash:

  • In place of a bullet character in a list.
  • To indicate an empty cell in a table.

Don’t capitalize the first word after an em dash unless the word is a proper noun.

En dashes

Use in ranges of numbers and dates, to indicate negative numbers, and as a minus sign. Use to connect compound modifiers under specific conditions.

Additional Information

Hyphens

Use to join words and connect prefixes to stem words. Don’t use two hyphens in place of an em dash.

For information about hyphenating specific technology words, see the Microsoft Style Guide A–Z word list. For information about hyphenating common words, see The American Heritage Dictionary and The Chicago Manual of Style.

Predicate adjectives

Don’t hyphenate a predicate adjective (an adjective that complements the subject of a sentence and follows a linking verb) unless the Microsoft Writing Style Guide specifically recommends it. Check the A–Z word list to find out.

Examples:

The text is left aligned.

The camera is built in.

Many viruses are memory-resident.

Noun modifiers

In compound words that precede and modify a noun as a unit, don’t hyphenate:

  • An adverb ending in -ly, such as completely, when it precedes another modifier.

Examples:

extremely stylized image

highly graphical interface

Note: Use adverbs sparingly. They usually aren’t necessary.

Hyphenate two or more words that precede and modify a noun as a unit if:

  • Confusion might result without the hyphen.

Examples:

built-in drive

high-level-language compiler

read-only memory

lower-left corner

floating-point decimal

line-by-line scrolling

scrolling line by line

up-to-date information

  • One of the words is a past or present participle (a verb form ending in -ed or -ing and used as an adjective or noun).

Examples:

left-aligned text

free-flowing form

well-defined schema

The schema is well defined.

  • The modifier is a number or single letter plus a noun or participle.

Examples:

two-sided arrow

5-point star

y-coordinate values

Suspended compound modifiers

  • Don’t use suspended compound modifiers, such as left- and right-aligned text, unless space is limited. Instead, spell out the entire phrase.

Example:

upper-right or lower-right corner

  • If you use a suspended compound modifier, include a hyphen with both adjectives. The first hyphen is followed by a space.

Example:

upper- or lower-right corner

  • Don’t form suspended compound modifiers from one-word adjectives.

Example:

uppercase and lowercase letters

Prefixes

Avoid creating new words by adding prefixes to existing words. Rewrite to avoid creating a new word.

In general, don’t include a hyphen after the following prefixes unless omitting the hyphen could confuse the reader:

  • auto-
  • co-
  • cyber-
  • exa-
  • giga-
  • kilo-
  • mega-
  • micro-
  • non-
  • pre-
  • re-
  • sub-
  • tera
  • Un-

Use a hyphen between a prefix and a stem word:

  • If a confusing word results without the hyphen.

Examples:

non-native

pre-provisioned

  • If the stem word begins with a capital letter.

Example:

non-XML

A prefix affects a word, not a phrase. For example, instead of non-security related, use unrelated to security.

When adding a prefix to a stem word results in a double vowel and each vowel is pronounced, don’t use a hyphen.

Examples:

reenter

cooperate

Additional information on hyphens

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