Usage of hyphen and dashes

What are they and how are they typed?

The hyphen is the shortest of them:                  -

Next longest is the en dash                             –

The longest is the em dash                               — 

These dashes are so named because an en dash is approximately the same length as an upper case ‘N’ and an em dash, the upper-case ‘M’.

The hyphen is easy to type as there is a hyphen key (which also serves the minus key) on all keyboards. However, care needs to be taken not to type an underscore ( _ )   when a hyphen (-) is needed, as they are usually on the same key. The most common use of the underscore is in URL addresses. The en dash and em dash are less easy. However, on a MAC keyboard, there is a simple short cut. To type an en dash, press the alt/option key and the hyphen key together, and to type an em dash, hold down the upper-case key while pressing the alt/option key and hyphen key together. It is less easy on a Windows keyboard, but a new emjoi keyboard makes it easier as it has a short cut. Otherwise, these dashes can be accessed on a Windows keyboard by holding down the alt key and keying 0150 for en dash and 0151 for m dash.

When is a hyphen used?

A hyphen is used to link compound words, often compound adjectives. Here are some examples of when a hyphen (and is not) used:

The new manager is a well-educated person. The new manager is well educated.

An up-to-date dictionary is now available. The new dictionary is up to date.

This is a twentieth-century publication. This book was published in the twentieth century. 

Hyphens can be used in numbers:

One-third of the recipients did not return their questionnaires

Sixty-five people ordered the new book in the first hour the shop was open.

This question is so easy that a five-year-old could answer it. 

There is a recent tendency not to hyphenate some compound words, such as: multinational, geophysics, whereas some compound words are still hyphenated, especially when it would otherwise cause confusion; for example, re-enter. However, words such as cooperation/co-operation are generally acceptable with or without a hyphen, in which case most dictionaries give both forms. For certain words, such as wellbeing/well-being, dictionaries may differ. In this case, writers should be consistent and use one or the other throughout their document. 

It is not usual to hyphenate capitalised multiple adjectives for example, National Trust members; but in some words, they are hyphenated; for example, Anglo-French relationship, because it could otherwise cause confusion. 

When a compound word includes an adverb ending in -ly it is not hyphenated; for example, a quietly spoken person. The same applies to the adverb very; for example, This is a very interesting story. 

Hyphens are subject to fashion and personal preferences; therefore, it is wise to consult an up-to-date dictionary if uncertain about the hyphenation of a particular word. Also, if a piece of writing is to be submitted to a university or publisher, the appropriate style guide should be followed. Rules and fashions regarding hyphenation can vary according to different versions of English. Most importantly, consistency is paramount. 

The En Dash (–)

The en dash is used in ranges of dates and numbers; for example:

Please consult pages 30­­–45 of the handbook to find the information you require.

The athlete spends 2–3 hours of each day jogging.

In Europe, the winter of 1963–64 was one of the coldest on record. 

However, please note the following examples where an en dash is not used:

Queen Victoria reigned from 1837 to 1901.

The train travels between 1000 and 1500 kilometres every day. 

Th en dash is also used to write scores, votes and directions:

India scored 356–7 in their second innings.

The motion was defeated 67–63

The London–Edinburgh express is a popular train.

(but note the em dash is not used in: This express travels from London to Edinburgh). 

The Em Dash (—)

Although the use of the em dash has always been popular in fiction writing, it is now popular in other types of writing, even in academic writing. A typical use of the em dash in fictional writing is:

We were walking through the field — suddenly a tree was struck by lightning — so we returned home immediately.

The em dashes strongly emphasise the words within them. Parentheses or commas could also be used, but they would not have the same powerful impact. 

The use of the em dash can express a sudden change of thought because something has happened; for example: It’s good to watch this television programme together — don't open the window, it's started to rain — because we all like the programme. 

In academic writing, the em dash is used much less often than either parentheses or commas. In fact, some people would advise against using the em dash at all in academic writing because if it is used excessively it can break up the continuity. However, it is used occasionally in academic writing when it is appropriate; for example; The new laboratory —such as it is — is a considerable improvement on the old one to conduct our experiments.

Some writers put a space between the em dash and the words that follow or precede it, while some do not. There is no specific rule on this, but it is essential to be consistent. 

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