Hyphen | Dashes | Em Dash | En Dash

Hyphens and Dashes

Hyphens are used for different reasons than dashes. The following paragraphs explain the distinctions.

Hyphen

Use a hyphen

• When two- or three-word modifiers precede the noun.
  
  cost-competitive semiconductor production
  
• To reduce confusion or ease the reading of compound words and some prefixes for words.
  
  re-sign (as opposed to resign), burn-in, P-N junction, non-deposition phase

NOTE: Most prefixes are no longer hyphenated. A usage table for common prefixes is in The Chicago Manual of Style.

• To add a prefix to a proper noun.
  
  mid-January timeframe
  
• To show relationship when the first element or prefix for a compound term must temporarily stand alone.
  
  one- or two-page description, high- or low-level radiation

Do not use a hyphen

• When a an adjective clearly modifies the noun following it.
  high volume manufacturing
• When compound modifiers follow the noun.
  
  high-volume semiconductor production that is cost competitive
  
• When compound modifiers combine an adverb and adjective.
  
  highly sensitive material
  optimally focused lens
  
• When adjectives are composed of foreign words (unless they are always hyphenated).
  
  in situ measurement
  a priori argument

Dashes

There are two basic types of dash: an em dash (-) and an en dash (-). When using dashes, keep in mind

Dashes are not surrounded by spaces.

The first word after a dash within a sentence is not capitalized unless it is a proper noun.

Em Dash

Use an em dash to

Set off an explanatory or appositive series

The company has established a worldwide customer base in all major markets-the U.S., Europe, Japan, Korea, and Taiwan.

Set off parenthetical elements more sharply and emphatically

The 1990 plan-both the planning process and the finished product-attests to the increasing level of maturity and effectiveness at SEMATECH.

Set off a phrase that typically requires commas, but one in which using commas would cause confusion

Knowledge from the SEMATECH member companies, America's equipment and material suppliers (SEMI/SEMATECH), and the Department of Defense (DOD) are brought into SEMATECH-along with information from American universities, research institutions, government laboratories and agencies, and the Semiconductor Research Corporation (SRC).

En Dash

Use an en dash to indicate a range.

May-June
pp. 21-34