Writing Essentials

6 The 15 Punctuation Marks

Fairly or unfairly, much of your professional writing will be judged based on how well it is written. Errors in punctuation stand out to many readers and suggest a lack of attention to detail or insufficient proofreading and internal document control. As such, this book places a heavy emphasis on being able to correctly use the 15 most common punctuation marks.

Let’s take a look at them one by one.

. (period)

Pretty much everybody has mastered this one, except when it comes into contact with quotation marks. Some folks call it a “full stop,” but the term used in North America is a “period.” Also, note that the common practice is now to have only one space after a period.

” (double quotation mark)

Yes, the problem I see here most is that some people put the periods outside the quotation marks. Believe it or not, periods land inside quotation marks with one exception: when there’s a citation after the quote, in which case the period would land after the citation. Here are two examples.

Sam said that “the period lands inside the quotation marks.

For in-text citations, the Purdue Online Writing Lab directs writers to “include the author, year of publication, and page number for the reference” (n.d., para. 8).

Commas also land inside quotation marks, except when there’s a citation. Interestingly, colons and semicolons always land outside the quotation marks.

With question marks and exclamation marks, there’s a logic to it; if the question mark or exclamation mark is part of the quote, then it belongs inside the quotation marks. If not, it lands outside the quotation marks.

One sentence-ending punctuation mark lands at the end of a quote. Never include two, such as a question mark and then a period.

If you’re wondering why periods and commas land inside quotation marks, I wish I could tell you there’s some logic to it, but there’s no logic; it’s simply the rule in North America. I don’t like telling students “that’s just the way it is,” but sometimes, well, that’s just the way it is.

‘ (single quotation mark)

This is a very rarely used quotation mark; it is only for quotes within other quotes. That is, you’re quoting one person who, in their comments, was quoting another person. Here’s an example.

Carlos said, “my favourite quote is ‘an eye for an eye leaves the whole world blind,’ which was said by Mohandas Gandhi.”

That’s the only time you ever need to use single quotation marks ever again. The rest of the time it’s double quotation marks all the way.

Students educated in Australia, Britain, or an education system created by British instructors (e.g., India) may have been trained to use single quotation marks much more often. Beware! Single quotation marks are barely used in North American English. (Some folks continue to use them, especially in novels, but they’re taking stylistic license.)

? (question mark) and ! (exclamation mark)

These characters are pretty easy, too. We’ve already mentioned the one exception about when they go inside or outside of quotation marks. One point I will make is that the exclamation mark is virtually unused in professional writing. There simply aren’t that many times when it is justified by the text. I really wouldn’t be surprised if they were entirely a relic of the past in 20-50 years.

‘ (apostrophe)

This looks just like a single quotation mark and is often the same key on the keyboard; however, this is a totally different punctuation mark. It is sometimes called an “inverted comma,” but this term isn’t used much in North America.

I should also say that, at the post-secondary level, you should 100% master this punctuation mark.


For real.

This punctuation mark has two purposes: showing possession or showing omission of letters. This punctuation mark does not indicate plurals (though, of course, plurals can have possession).

Fair or unfair, apostrophe errors are a red flag in the professional world for a low level of professional diligence. If you have apostrophe errors, they will be the first to be detected and they will demonstrate that you didn’t have anybody else look at your work before considering it complete.

So, enjoy this Oatmeal article about when to use apostrophes: http://theoatmeal.com/comics/apostrophe.

; (semicolon) and : (colon)

Here’s a mind-blowing revelation: semicolons are easier to use than commas.

Jennifer Lawrence: Mind Blown

Commas are much more difficult to use, but most people are more comfortable using them.

The rules on semicolons are relatively simple. Here’s a video that provides an overview:

Semicolons are used to link ideas when something stronger than a comma is needed. A semicolon has three main functions. Here are the first two:

Semicolon Rule #1

Use a semicolon to join closely related into one sentence:

If the two independent clauses are closely related in content, then a semicolon may be appropriate.

Here is an example:

Scott was impatient to get married; Sharon wanted to wait until they were financially secure.

The subject in both sentences are both strongly related; indeed, in this case, they are engaged!

Semicolon Rule #2

Use a semicolon to link two sentences joined by a (such as however, therefore, finally, or moreover)

Transition words are a great way to connect your sentences. Here is an example:

Canadian History is a rather dull class; however, it is a requirement for the elementary education program.

You may have noticed that, in both examples above, a semicolon works the same way a period does. If you could put a period there, then you can put a semicolon there—as long as both sentences are related. The semicolon simply connects the ideas more closely as part of one key idea and makes the pause between them a little shorter.

The main rule you must remember is that if you use a semicolon in this way, the clauses on either side of the semicolon must be complete sentences. You cannot use a semicolon to introduce a phrase or fragment.

Complete sentence; complete sentence.

Also remember that you cannot simply use a comma instead of a semicolon to link the two clauses; doing so would result in a .

Semicolon Rule #3

Use a semicolon to separate items in a complex list where one or more of the items have internal punctuation

Take a look at this sentence:

After travelling the world extensively, I consider my favourite places to be Paris, France, Copenhagen, Denmark, Vienna, Austria, Kyoto, Japan, Dubai, UAE, and New York, USA.

Was it hard to read at all? It probably was because not everybody will know which of those places are cities and which are countries. They’re grouped together, but it’s confusing to read. This is where the third function of the semicolon comes in.

Here’s a correct example:

After travelling the world extensively, I consider my favourite places to be Paris, France; Copenhagen, Denmark; Vienna, Austria; Kyoto, Japan; Dubai, UAE; and New York, USA.

In this case, the semicolon separates long, complex list items that contain commas within them. Without the semicolon, we have a complicated sentence that is difficult to read. In this usage, the semicolon is sometimes known as a “super comma.” (Personally, I avoid this usage if I can.)

As with the semicolon, a colon is another type of punctuation that confuses a lot of people. Thankfully, it serves a simple purpose. Here is a video to review its use:

Use a colon to introduce amplification in the form of an example, explanation, quotation, summary, or list.

Keep in mind that when correctly used, colons are only placed where the sentence could come to a complete stop (i.e., you could put a period there instead).

Amplification The hurricane lashed the coastal community: within two hours, every tree on the waterfront had been blown down.
Example or definition The tour guide quoted Gerald Durrell’s opinion of pandas: “They are vile beasts who eat far too many leaves.”
List Today we examined two geographical areas: the Nile and the Amazon.

Remember that when introducing a list, example/definition, or quotation with a colon, whatever comes before the colon should be a complete sentence.  You should not write something like this:

Today we examined:  x

Three important objectives we must consider are: x

If these clauses cannot end in a period, they should not end in a colon. Whatever comes after the colon can be a fragment or list; it does not have to be a complete sentence.

, (comma)

This is by far the most difficult punctuation mark to master. However, if you start following what I’m saying above about dependent clauses and independent clauses, you’ll see that a lot of them are joined by a comma.

In elementary school, you were told that a comma represents “a pause.” That’s what they told you because they didn’t think they could explain the difference between an independent clause and a dependent clause. But, now that you’re the post-secondary level, you’re ready.

Commas are frequently used in lists, such as “the French flag is red, white, and blue.” That’s pretty easy.

The tricky part is being able to join an independent clause and a dependent clause and identifying when that is happening.

“I walked to the store.”

That’s an independent clause; it can stand as its own sentence.

“despite knowing it was probably closed.”

That’s a dependent clause; it cannot stand as its own sentence.

I can join them with a comma, though.

“I walked to the store, despite knowing it was probably closed.”

That comma isn’t a pause. It’s joining those two clauses and showing a relationship. If reading aloud, you would probably have a brief pause there, but that’s a side effect of a comma, not the purpose of a comma.

Stop thinking of a comma as a pause and start thinking about it as a tool. (To see what erroneously happens when certain actors treat a pause as a need for a comma, look here: https://pbs.twimg.com/media/CsZnEhEWAAAxfsd?format=jpg&name=small.) It is widely misused and often omitted, but commas are necessary to show relationships in sentences.

Commas can also be used like parentheses.

“I was going to the grocery store, list in hand, to buy ice cream, strawberries, and chocolate syrup.”

If I cut “list in hand” from the sentence, the commas on either side are not needed. (The rest of the text constitutes a complete sentence.) One of my students once told me that she called that a “drop in” clause; I love that term and still teach it today. Technically, those are called parenthetical commas, though.

Those are the three main uses for commas: lists, parenthetical clauses, and joining dependent clauses to other parts of sentences.

The article “Comma Quirk Irks Rogers” provides an example of how a punctuation error can have real world costs and consequences. One comma error in a 10-page contract cost Rogers Communication $2 million dollars (Robertson, 2016). If you need further evidence, read about the case of the trucker’s comma that went all the way to the supreme court, resulting in a $10 million dollar payout (Nast, 2017).

There is some debate about whether to place a comma before the “and” used before the final listed item. This comma, referred to as the Oxford Comma since it is required by Oxford University Press, is optional in many situations. For an optional piece of punctuation, the Oxford Comma has stirred up a surprising amount of controversy.

Here’s a video that explains that controversy, if you’re interested.

() (parentheses) and [] (brackets)

Although “square brackets” (correctly called “brackets”) can be used as an aside within rounded parentheses (often mistakenly called “brackets,” which they are not), they are most often used for replacing words in quotes to show context.

“I was speaking to [Sam] about punctuation use in professional writing.”

What this tells the reader is that the text originally read as follows:

“I was speaking to him about punctuation use in professional writing.”

If I leave “him” alone, the reader won’t know who I’m talking about. So, I amend the quote by changing “him” to “Sam” and putting “Sam” in brackets to show the amendment to the quote. This is very common among journalists, who ask a few questions and then decide only to use a quote from a later question. Because, by this time, the person being interviewed was using pronouns, the journalist has to edit the quote so the reader knows who the pronouns referred to.

Parentheses are used just as you think: to show information that is interesting or qualifying, but not critical to the sentence. They are also used to show citations; the period at the end of the sentence would follow the parentheses.

– (hyphen)

A hyphen is used to create a compound term.

For example, if two people have recently ended a romantic relationship, you might say they’ve gone through a “break-up.” As a verb, no hyphen would be necessary: “Jane and John are breaking up.”

However, turning that verb into a compound noun required a hyphen to show that the two words were being treated as a single term. This also comes up a lot with adjectives.

You may want to say that a person is detail oriented, but to do so as an adjective, you would say that they are “a detail-oriented person.” They aren’t a detail and they aren’t merely oriented; the two terms act as one to describe the person.

Hyphens are also used in numbers, such as “twenty-seven,” but we would almost always write “27” instead, so it doesn’t come up too much. (You would only write “Twenty-seven” if it was the first word of a sentence or a part of a proper noun.)

By the way, there are no spaces on either side of a hyphen; it touches the letters on each side.

— (dash)

Now, a dash looks like a hyphen and is sometimes formed by typing two hyphens in a row, but it performs a completely different task. In many respects, the dash performs a similar function to parenthetical commas (the “drop in” clause) or parentheses.

The dash sets information in the sentence aside for the reader.

“Sam wrote a lengthy reading module about punctuation—posted well before the first graded quiz—that helped me understand the 15 punctuation marks.”

Also, as with hyphens, there are no spaces on either side of a dash. It goes right up to the words on either side.

In terms of weight, I consider parenthetical commas to be the least disruptive to a sentence, followed by dashes, and then parentheses. As a writer, you need to choose how severe a disruption you want. With parentheses, the text is almost removed from the sentence. With dashes, the text is a strong aside. With parenthetical commas, the text is almost seamlessly included in the sentence.

… (ellipses)

These dots indicate that something has been left out of a sentence.

“The engineer had a number of objections to the plans as presented: materials, location, local bylaws…and, most of all, the cost.”

In the sentence above, I’m showing that there were more objections, but I’ve omitted them. Perhaps there were too many to list or perhaps they were less important, but I need to show you that they’ve been omitted.

If the ellipsis ends a sentence, add a fourth period to show that the sentence has ended and your next word isn’t resuming the previous sentence.

Sometimes people want to use an ellipsis to show a pause or a trailing off on thought, but that’s taking license with the punctuation mark. People do it, though….

/ (slash)

This is a seldom-used punctuation mark with a specific purpose. It shows that the text needs to change based on context. Below are the two most frequent examples.

“I want ice cream and/or strawberries.”

That means the person wants either or both of the food options. It’s like programming code for a sentence.

“We’re going to write a biography of every Canadian prime minister. Each one will focus on his/her time in public office.”

There have been prime ministers of Canada of two different genders, so the speaker is including two pronouns with a slash to show that the pronoun may change, depending on which prime minister is being discussed.

However, contemporary language is moving away from binary gender definitions to be more inclusive of gender diversity. As such, the expressions “he/she” or “him/her” are quickly going out of style because they suggest the old binary gender definition. There are more than two genders and professional writing needs to be inclusive of that. You can use “they” or “them” to be inclusive, which is the new trend in professional writing.

You may also have heard of the slash being called an “oblique” or “forward slash.” It’s the same punctuation mark. The backslash is not a punctuation mark; it is only used in coding and mathematics.

So, those are the 15 punctuation marks. By the end of your first post-secondary writing course, you should be able to correctly use all of them.

Added help

If you’re looking for practice quizzes to help you study, you might find this to be a great website: http://www.grammarbook.com/interactive_quizzes_exercises.asp.

They have free practice quizzes with the answers available when you complete a quiz; they also provide explanations when you’ve made a mistake. There are a number of different quizzes for helping on different issues that you may wish to focus on for your own improvement.

Further, if you haven’t used Grammar Girl, this is just one example of the content on that website (dealing with commas): http://www.quickanddirtytips.com/education/grammar/how-to-use-commas-a-summary. That site has dozens of articles about different technical writing questions, such as homonym issues, different types of clauses, or punctuation usage. Any time you have a question, searching this site is a good way to go. (PS: Grammar Girl has actually gone downhill in recent years and is almost a clickbait website, so make the most of it, but turn off the ads. Gah. So many.)

I hope these added resources are valuable and, in some cases, mildly amusing.

In professional writing and at the post-secondary level, you should be able to use all 15 of these punctuation marks correctly. Misuse can change the meaning of a sentence in some unfortunate ways. And, fair or unfair, your work, both professionally and academically, will be judged for errors in punctuation.

The only way to master these writing tools is to choose to do so through study, observation, and practice. Notice when you see errors in your writing and the writing of others and start to read for form, not only content, and develop good writing habits. There’s no shortcut. However, being able to identify and distinguish independent and dependent clauses will go a long way to helping.

For writers, a major milestone is the transition from reading for content to reading for form. As you study the craft of writing, you should be reading not only for the content in sentences, but also for the form of those sentences, themselves. I hope you’re seeing how sentences are structured and punctuated and how writers use the tools available to show meaning, emphasis, nuance, and relationships. When you read, look beyond the meaning; look for the form and craft of writing itself. You’ll learn so much by doing so.


Fogarty, M. (2008, March 21). Which versus that. Quick and Dirty Tips. https://www.quickanddirtytips.com/education/grammar/which-versus-that-0

Giphy.com. (2013). Happy Jennifer Lawrence [GIF]. https://giphy.com/gifs/mind-blown-happy-jennifer-lawrence-C0z65GND5PgzK

Purdue Online Writing Lab. (n.d.). In-text citations: The basics. https://owl.purdue.edu/owl/research_and_citation/apa_style/apa_formatting_and_style_guide/in_text_citations_the_basics.html

Nast, C. (2017, March 17). A few words about that ten-million-Dollar serial comma. The New Yorker. https://www.newyorker.com/culture/culture-desk/a-few-words-about-that-ten-million-dollar-serial-comma

Robertson, G. (2006, August 6). Comma quirk irks Rogers. The Globe and Mail. https://www.theglobeandmail.com/report-on-business/comma-quirk-irks-rogers/article1101686/

WhimOfTheWorld. (2010). Elaine and Mr. Lippman: Exclamation points. https://www.youtube.com/watch?v=VSKn8RlD7Is


This chapter was adapted from Effective Professional Communication: A Rhetorical Approach by Rebekah Bennetch, Corey Owen, and Zachary Keesey, which is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Bennetch, Owen, and Keesey adapted their chapter from “Technical Writing Essentials” by Suzan Last (on BCcampus). It is licensed under Creative Commons Attribution 4.0 International License.


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