It’s hard to believe that a tiny stroke on the page can cause so much confusion and misunderstanding. Yet the hyphen (-) and the dash (a longer stroke) do just that.
Many people think the hyphen and the dash are the same thing. Although they do look similar, there are some important differences. First there’s the length—the hyphen is shorter than the dash—and then there’s the purpose. Let me explain.
The hyphen (-) punctuates words. You would use a hyphen to join two words together because they have a single meaning. For example: ‘We met at a get-together but she gave me the brush-off’. You would also use a hyphen when you want to join words together to form a word compound used as an adjective (which is a fancy way of saying ‘joining words together to describe a person, place or thing’). For example: ‘The folders are blue-black’ or ‘The blue-black folders’. (You’ll notice that the adjective compound can come before or after the word it’s describing.)
Number compounds are also hyphenated. For example: ‘My mother is ninety-nine years old’ not ‘My mother is ninety nine years old’ and ‘I only ate two-fifths of the chocolate, so what are you complaining about?’ not ‘I only ate two fifths of the chocolate, so what are you complaining about?’ (Although it’s probably better to write: ‘I left more than half the chocolate for you!’)
When a word has certain prefixes like ‘ex’ or ‘semi’ or ‘un’, you also usually need to whack in a hyphen. For example: ‘It’s un-Australian to dob in your mates.’ It’s a bit confusing though and too hard to remember which words are hyphenated and which are written as one word, or two separate words. Your best defence is to refer to a good dictionary (for example, the word ‘unplaced’ does not have a hyphen according to the Macquarie Dictionary).
Now, the dash is a whole different kettle of fish. Longer than the hyphen, it’s known to typesetters as an ‘em rule’ ( — ) or ‘en rule’ ( – ). An en rule is generally about half an em.
Em and en rules can be spaced (a space on either side of the dash) or unspaced (no spaces either side). An example of an unspaced em rule is: ‘I proofread my report—the one that took me all day to write—and found several errors’.
The style recommended for Australian government publications is an unspaced em rule; however, your organisation might have different ideas. So check your organisation’s own style guide to find out their preferred style. If your organisation doesn’t have a style guide, choose a style (for example, spaced en rule) and then use that style consistently throughout the document.
Now that you know you can use either an em or an en rule to show a dash, when should you use a dash? A dash is particularly useful when you want to gather together a group of words and lead into a summation of them. For example: ‘The fresh paint, the new carpet, the re-designed counter—our refurbished customer service centre completed on schedule.’
Or perhaps you have an afterthought: ‘He turned up to work late again—perhaps he’s been out on the town again.’ You can also use it when you want to add interesting bits of information to your sentence. For example: ‘The local environment committee—a dedicated group of people—produced an insightful report.’ It can also add some drama: ‘My daughter slipped from her horse—into the mud.’
If you’re one of the many people who think all this talk of em and en rules is too confusing and pedantic, you’re not alone. Although the world (or your sentence) won’t come crashing down on top of you if you accidentally use a hyphen when you should be using a dash, it does look sloppy if you’re inconsistent within the one document. For example, don’t use a spaced en rule in one part of the document and an unspaced em rule in another (this can easily happen when you copy and paste from different documents).
Still confused? Time to call in the professional editor!