A period denotes the end of a sentence (a sentence is a group of words containing a subject and predicate). For example:

He went to Las Vegas last week.

They have a happy family.

Note that, traditionally, sentences ending with a period are followed by two spaces. In modern electronic media, however, it is common to use only one space because it is more visually appealing.

A comma has a number of uses, as follows:

1.  Separate a list of items. This is one of the most common uses of a comma. Frequently, a comma is included before the conjunction and in the final element of a list, though not always. This is a matter of style. The important thing is to be consistent. For example:

I like reading, listening to music, taking long walks, and visiting my friends.

They need books, magazines, DVDs, video cassettes, and other learning materials for their library.

2. Separate phrases (clauses). This is especially true after a beginning dependent clause or a long prepositional phrase. For example:

In order to qualify for your certificate, you will need to take the exam.

Although he wanted to come, he wasn't able to attend the course.

3. Separate two independent clauses that are connected by a conjunction such as and, but, or, while, and yet. For example:

They wanted to buy a new car, but their financial situation would not allow it.

I'd really enjoy seeing a film this evening, and I'd like to go out for a drink.

4.  Introduce a direct quote. For example:

The boy said, "May I please have an extra scoop of ice cream on my cone?"

Her doctor declared, "If you don't stop smoking, you run the risk of cancer."

5.  Separate appositives (a noun, or noun phrase) or non-defining relative clauses. For example:

Bill Gates, the richest man in the world, lives near Seattle.

My sister, who is a fantastic tennis player, is in great shape.

NOTE: Be careful not to overuse commas. They should help readers, not hinder them. As a basic rule, if the comma does not replace a word like and or or then it is probably not necessary.

An apostrophe has a number uses, as follows:

1. Contract a word. This is probably the most common use. The apostrophe replaces letters removed in words or between two words: For example:

It’s a beautiful day

Isn’t that Bill Gates?

He was in born in ‘82.

Check if an apostrophe is appropriate in these cases by replacing it with the full text. For example, It’s a beautiful day sounds correct when replaced with It is a beautiful day. But I mixed the egg yolk with it’s whites does not sound correct when replaced with I mixed the egg yolk with it is whites, therefore the apostrophe is not appropriate and should not be used.

2. Indicate possession. For example:

The boy’s hat.

The police officer’s car.

When the possessor is plural, but does not end in an s, the apostrophe precedes the s. For example:

The children’s books.

The women’s movement.

But when the possessor is plural, the apostrophe follows the s. For example:

The babies’ clothing.

The high school students’ prom.

3. Indicate time or quantity. For example:

In one year’s time.

The worker gave a week’s notice. (or The worker gave two weeks’ notice.)

The question mark is used at the end of a sentence to indicate a question. For example:

Where do you live?

How long have they been studying?

The exclamation point is used at the end of a sentence to indicate great surprise. It is also used for emphasis when making a point. For example:

That ride was fantastic!

I heard they are having a baby!

Be careful not to use an exclamation point too often since it can diminish its impact. Never use a double exclamation point.

A colon is typically used for two purposes, as follows:

1. Introduce additional details, an explanation, an example, or a direct quotation. For example:

He had many reasons for joining the club: to get in shape, to make new friends, to lose some weight, and to get out of the house.

She resigned her job for the following reasons: bad pay, horrible hours, poor relations with colleagues, and her boss.

2.  Introduce lists containing the words as follows or the following. For example:

He used a colon for the following purposes:
1) To introduce a list.
2) To introduce additional details.

A semicolon generally has two uses, as follows:

1. To separate two independent clauses. One or both of the clauses are short and the ideas expressed are usually very similar. For example:

He loves studying; he can't get enough of school.

What an incredible situation; it must make you nervous.

2. To separate groups of words that are themselves separated by commas. For example:

I took a holiday and played golf, which I love; read a lot, which I needed to do; and slept late, which I hadn't done for quite a while.

They plan to study German, for their travels; chemistry, for their work; and literature, for their own enjoyment.

There are several uses for the hyphen, as follows:

1. To divide a word across two lines of text. For example:

The hospital noticed that the patient suffered from acute intra-
abdominal pain.

Never before had he seen such clear div-
ision of labour amoung work groups.

2. To separate compound words. For example:

The movie was a hair-raising thriller.

His job was to cross-reference the titles with the computer entries.

Note that there are many rules governing the use of compound words, some of which are contradictory depending on the dictionary used. For a full explanation of compound words, please consult the additional references at the end of this page.

3. To separate prefixes ending in a vowel with words beginning with a vowel. For example:

He was assigned to co-ordinate the entire event.

She installed an anti-occilation device.

4. To describe pronunciation of words. For example:

Demo-cra-cy

Lab-or-a-tor-y

There are two types of dashes: an em dash and an en dash. An en dash twice as long as a hyphen and is written by entering two dashes ("–"). The em dash is three times as long as a hyphen ("—"). Styles vary, but generally em dashes appear with a space on either side, while en dashes have no spaces before or after they are written.

Em dash

1. To mark a suspension of the sense, a faltering in speech, or a sudden change in topic. For example:

No doubt she could see — who could not? — the dazzling sunset.

Instead I wrote — but let me quote his own words.

2. To set off a parenthetical expression whenever commas appear in that expression. For example:

The face — thin, harsh, cold, and forceful — was disquieting.

The book — a portion, it may be noted, was torn — was her favourite.

Be careful not to use em dashes where parentheses are more suitable, for instance when text adds information to the sentence. This can clear up an otherwise confusing sentence. For example:

Confusing: The younger group — those under 40 — performed

better than the older group — those over 40.

Clearer: The younger group (those under 40) performed better than the older group (those over 40).

3. To mark unfinished sentences. For example:

"But if we —" he began.

"It’s best if you —" He stopped suddenly.

En dash

The years 1990–1999 were the last decade of the 20th century.

You can take the Richmond–Vancouver bus to get downtown.

The quote was from pages 6–7 of the text book.

An en dash is never used if the numbers are preceded with from. In such cases, the word to is inserted. For example:

Wrong: The railway was constructed from 1878–85.

Right: The railway was constructed from 1878 to 1885.

Wrong: The quotation was taken from pages 6–7 of the book.

Right: The quotation was taken from pages 6 to 7 of the book.

Parentheses are used to highlight an expression where commas and em dashes are inappropriate, notably when text is an aside or has no essential connection to the sentence. For example:

The samples that were collected (under extremely difficult conditions) were the best.

The song is attributed (whether rightly or wrongly) to more than one lyricist.

If the text is related to the sentence, then it should appear between commas or em dashes. For example:

The samples were collected — many during the winter — and they were the best.

The song is attributed, as is often the case, to more than one lyricist.

Note that when parentheses are are part of a sentence, sentence-ending punctuation appears outside the closing parenthesis. When the parentheses are a sentence itself, the punctuation appears inside the closing parenthesis. For example:

It has been noted that the samples were collected under extremely difficult conditions (though not so difficult as to prevent them from being collected).

(Several of the sample were collected under very difficult conditions.)

Brackets are generally used in the following situations:

1.  To enclose editorial remarks. For example:

As a negatif [sic] force, the Ros[s]eta Stone is unmatched.

The literary efforts of Homer mark the beginning of epic poems [though Homer may have made this style popular, he may not have invented it].

2.  To denote additional parenthetical text already in parentheses. For example:

The mountains were referred to the Peaks (or the Peaked on this
side [i.e., the Canadian side] of the boundary).

Scarring can be a result of the disease (opinions vary as to the extent [Rogers, 1990]).

Quotation marks are generally used in two situations, as follows:

1.  To mark direct quotations. For example:

"Get thee to a nunnery," said the cleric to his sister.

She said to the tyke, "I’ll be here when you get out of school."

2.  To emphasize words or phrases from surrounding text. For example:

The "working principle" of punctuation is emphasis.

The sign indicated a "big sale," but only three items were discounted.

Note that under these circumstances quotation marks can be used more or less interchangeably with italics. Always use one method consistently.

Ellipses are typically used in the following situations:

1.  To indicate an omission. For example:

We usually count from one, two, three...eight, nine, ten.

As Shakespeare noted, "...get thee to a nunnery."

Note that when an omission occurs at the end of a sentence, a fourth point is used to denote the period. For example:

He quoted Shakespeare as saying "...get thee to a nunnery...."

2. To demonstrate a lapse of time, typically in speech. For example:

He mused, "Hm-m. Yes, malaria...mosquito infection, I believe...tricky thing."

"I happen to think...," he stammered "that...well, that you are wonderful."

Canadian Style: A Guide To Writing And Editing. Toronto: Dundurn Press Limited, 1997.

The Chicago Manual of Style. 15th Ed. Chicago: University of Chicago Press, 2000.

Strunk, W. Jr. And E.B. White. The Elements of Style, 4th Ed., New York: Macmillan, 2000.

Truss, Lynne. Eats, Shoots and Leaves, New York: Gotham Books, 2004

Words Into Type. 3rd Ed. New Jersey: Prentice Hall, 1974