If you want your written English to be more effective and elegant, you should use the colon and semicolon correctly. While they may appear to be similar, they have very different uses. In brief, the colon is used to provide a pause before introducing related information, while the semicolon is merely a break in a sentence that is stronger than a comma but not as final as a full stop

• Do not use a colon in a complete sentence after phrases such as ‘including’, ‘such as’, and ‘for example’. Phrases like these already indicate to the reader that a list of examples will follow, there is no need to introduce them with a colon; it would be redundant.

Incorrect: New Zealand has many types of fruit, such as: apples, nashi pears and grapes. Correct: Many birds are found in New Zealand including kiwi, tui, weka and kea.

• Do not use a colon after a preposition (such as ‘in’), or a verb, that introduces a list.

Incorrect: The medical student excelled in: surgery, diagnostics and trauma. Correct: The new law student excelled in surgery, diagnostics and trauma.

• Do use a colon to introduce an item or a series of items, or provide an explanation, but only if its use is not contrary to rules 1 and 2 above.

Do not capitalise the first item after the colon in a list (unless it’s a proper noun). Correct Use to Introduce a List: The store carried all the items the new teacher needed: pens, paper, printer toner and folders. Correct Use as an Explanatory Tool: The cafeteria served the type of food most preferred by students: noodles.

• A colon instead of a semicolon may be used between independent clauses when the second sentence explains, illustrates, paraphrases, or expands on the first sentence.

Correct: He got what he worked for: he really earned his retirement.

• If the material following the colon is a dependent clause or phrase, do not capitalise the first word (unless it’s a proper noun).

Correct: He got what he worked for: a happy retirement.

• Do use a colon when restating an idea. If the material following the colon constitutes a full sentence, you can choose to capitalise the first word or not. Some writers and editors feel that capitalising a complete sentence after a colon is always advisable. Others advise against it.

Correct: Remember the old adage: Pretty is as pretty does.

• When two or more complete sentences follow a colon, capitalise the first word following the colon.

• Also, capitalise the first word of a complete or full-­sentence quotation that follows a colon.

Correct: Mother announced to all present: “Mary is getting married.” Correct: The teacher gave us three rules to follow: Be on time. Work hard. Share your knowledge.

• The colon can be used to emphasise a phrase or single word at the end of a sentence. An em-dash can be used for the same purpose.

Correct: After three weeks of deliberation, the jury finally reached a verdict: guilty.

There are three basic types of ‘dashes’; they have different uses and cannot be used interchangeably. Here’s how to tell the difference and use each correctly.

The Hyphen

A hyphen (-) is used to

• separate syllables of a word when there is a line break on a page.
• connect two words that function as a particular concept, or when linked together will form a particular modifier.

Examples:

The red-haired girl.

Low self-esteem is a common problem among students.

• connect grouped numbers, like a phone number 09-860-5086.
• write URLs and email addresses, such as hyphen-dash.com
• spell out words letter by letter; for example, pandemonium is spelt p-a-n-d-e-m-o-n-i-u-m.

How to use a Hyphen

• The hyphen does not indicate a range of numbers, like a date range, which is the job of an en-dash.
• Adverbs ending in ‘-ly’ generally should not be hyphenated. That is, it would be grammatically incorrect to write ‘the dimly-lit room’.
• Two or more words that collectively act as an adjective should be hyphenated when they appear immediately before the noun they modify. This helps prevent misreading and ambiguity.

Example:

The company requires ‘more experienced employees’ (more employees with experience), or does it require ‘more-experienced employees’ (employees with more experience)?

• To type a hyphen in MS Word, for both Windows and MAC OS use the Hyphen or Dash key.

The En-Dash

The en-dash (–) is used when writing about a range of things that are related in a continuous way. It is commonly used to indicate a closed range of values such as numbers, dates, pages, scores or time.

Examples:

The 2010–2011 season was our best yet.

You will find this material in chapters 8–12.

The All Blacks beat the Wallabies 39–10 in the final game of the season.

An en-dash can also be used to indicate numbers in an open-ended range, such as ‘Hillary Mantel (1952–)‘.

Prefixes

En-dashes are also used to connect a prefix to a proper open compound; for example, pre–World War II. In this example, ‘pre’ is connected to the open compound ‘World War II’.

Special usage case: compound adjectives

When a compound adjective is formed with an element that is itself an open compound or hyphenated compound, some writers replace the customary hyphen with an en-dash. This is an aesthetic choice more than anything.

Hyphen: She is an award-winning novelist.

En-dash: She is a National Book Award–winning novelist.

How to use an En-Dash

• The en-dash is about as wide as an uppercase N. The en dash (–) is slightly wider than the hyphen (-) but narrower than the em-dash (—).
• There should be no space between the en-dash and the adjacent material.
• Depending on the context, the en-dash is read as ‘to’ or ‘through’. If you introduce a span or range with words such as ‘from’ or ‘between’, do not use the en-dash.

Correct: She served as president from 2012 to 2018.

Incorrect: She served as president from 2012–2018.

• Inserting an en-dash in MS Word:

For Mac: press ‘Option + Hyphen key’.  Word will automatically convert it to an en-dash. On some Mac keyboards, the Option key is called ‘Alt’.

For desktop PC: press ‘Ctrl + Minus’ on the numeric keypad (the number section on the far right of your keyboard). The trick will not work if you press the Hyphen key on the typewriter section of the keyboard.

For PC-laptop: since many laptops do not have easily accessible numeric keypads, the en-dash insertion is a bit trickier. Type a space followed by a hyphen like -this. Word will automatically convert the hyphen to an en-dash like –this, but you will have to go back and delete that space like–this.

The Em-Dash

Depending on the context, an em-dash (—) can be used as a substitute for a comma, colon, semicolon or brackets.

Em-dashes are commonly used to

• indicate a break in thought or sentence structure; for example, “Will he — can he — find out the missing child?”
• introduce a phrase added for emphasis, definition or explanation. In such cases, em-dashes work better than commas or brackets to set apart a unique idea from the main clause of a sentence: ‘Sometimes writing for pleasure — rather than for fame or money — is really quite enjoyable.’

In this way, too, an em-dash can separate an inserted thought or clause from the main clause:

‘I can’t believe how pedantic Ann is about grammar — doesn’t she have anything better to do?’

• to substitute for part of a word left unfinished at the end of a sentence for reasons beyond the narrator or speaker’s control.

Example:

‘It was dark and silent in the woods, wet leaves occasionally brushed his arms as he crept along, and then a loud cra—’

Note that, in this case, the dash is always written solid next to the unfinished piece-of-a-word which precedes it. (If the sentence merely tails off into silence, we use, not a dash, but a suspension in the form of an ellipsis.)

• indicate interrupted dialogue or speech.

Example:

“I reached in and pulled the taser out of my backpack —”

“No! In front of the police?” she said.

The double em-dash is used to indicate missing letters in a word, either because the material is missing or illegible, or to conceal a name:

The company and Ms S— — agreed to settle the case.

The triple em dash is used to indicate missing words:

I admire — — — too much to expose him in this article.

How to use an Em-Dash

• The em-dash is as wide as an M.
• Based on the style convention you prefer, either set the em-dash off with a single space on each side (AP style) or omit these spaces (CMOS). Whichever you choose, use it consistently throughout your document.
• The em-dash is never used in place of a hyphen, after a colon or after a heading. It is not used to introduce a direct quotation, except sometimes in novels, but this is not a usage that should be encouraged.
• When using an em-dash in combination with other punctuation, note that a question mark or an exclamation point — but never a comma, a colon or a semicolon, and rarely a period — may precede an em-dash.

Example:

All at once Simon — was he out of his mind? — raised his pistol to the captain’s head.

• When an em-dash falls between the end of one line and the beginning of the next, you should try to ensure that the em-dash is placed at the end of the first line and not at the beginning of the second, if you can. Most word processors will not do this automatically, however, and it will require some fiddling.
• Inserting an em-dash in MS Word:

For Mac: press ‘Option + Shift + Hyphen key’.  Word will automatically convert it to an em-dash. On some Mac keyboards, the Option key is called ‘Alt’.

For desktop PC: press ‘Alt + Ctrl + Minus’ on the numeric keypad (the number section on the far right of your keyboard). The trick will not work if you press the Hyphen key on the typewriter section of the keyboard.

For PC-laptop: since many laptops do not have easily accessible numeric keypads, the em-dash insertion is different, but luckily, very easy. Just write two hyphens with no preceding or following space like–this. Word will automatically insert an em-dash instead of the two hyphens like—this.