Wikipedia:Hyphens and dashes

This is an explanatory essay about the Wikipedia:Manual of Style. This page provides additional information about concepts in the page(s) it supplements. This page is not one of Wikipedia's policies or guidelines as it has not been thoroughly vetted by the community.

This essay introduces the basics of hyphens, minus signs, en dashes, and em dashes in one easy lesson.

There are at least eight different horizontal dash-like characters of varying lengths defined in Unicode. Wikipedia uses four: the hyphen (sometimes called the hyphen-minus), the minus sign, the en dash, and the em dash.

Hyphen ("-", MOS:HYPHEN) (actually the hyphen-minus character in ASCII or Unicode character sets) are used in many ways on Wikipedia. They are the only short, horizontal dash-like character available as a separate key on most keyboards. They are used:

• in names, such as "Julia Louis-Dreyfus" and "Sainte-Ode",
• in compound modifiers, as in "hard-boiled egg", "small-appliance industry", and "real-valued function",
• for prefixes and suffixes, such as "mid-Atlantic" and "shell-like",
• when prefixing a capitalized word, such as "un-Christian",
• to avoid double vowels, such as "semi-independent"
• when writing out fractions like "one-third" or "three-fifths"

In some styles, minus signs are represented using an en dash instead of a minus sign or a hyphen. This is not done in Wikipedia. In math formulas a hyphen-minus codes for a minus sign, but in text − produces the minus sign (see below).

En dash ("–", MOS:ENDASH) are slightly longer than hyphens. They are used:

• in date ranges, such as 1849–1863,
• to join two names in a phrase, such as the Michelson–Morley experiment,
• in multi-part prefixes, such as "post–World War II", although for those, either a hyphen or an en dash can be used; British publications use hyphens, and American publications use en dashes.^{[dubious – discuss]}

Spaced en dashes are also used to set aside a phrase – like this – in a sentence; when this is done, it is preferred that a non-breaking space be used before the en dash and a normal one after it:  – .

Em dash ("—", MOS:EMDASH) are even longer and are used solely to set aside a phrase—like this—in a sentence.

Em dashes and en dashes, when used to set off parentheticals, are interrupters, along with parentheses (round brackets) and commas;^[1] the principal differences are that parentheses are used to offset text of an optional or "aside" nature, commas are used to offset text that flows as an integral part of the sentence, and dashes are used to offset text in an emphasized manner.

Minus sign ("−", Wikipedia:Manual of Style/Mathematics#Minus sign) are available for negative numbers such as −4 but can cause difficulties in sorts and searches.