Dashes, colons, and commas

Dashes, Colons, and CommasEditing is part science and part art form. There are certain grammatical rules you need to apply to your writing, but you also need your text to tell a story, and how you use your punctuation can add style and nuance. You might think this concept is more important when writing fiction, but I think it applies equally to business writing, which, let’s be honest, can be a little dry.

In response to some requests I’ve received, today I’m going to focus on three punctuation marks—semicolons, colons, and dashes—that, when used correctly, can add flavor to your writing and paint a clearer picture of the message you want your readers to receive.

Semicolons: Keeping Ideas Close

The semicolon doesn’t get much respect these days. Though Abraham Lincoln believed it to be a “useful chap,” author John Irving believes that “[n]o one knows what they are anymore. . . . If you’re not in the habit of reading nineteenth-century novels, you think that the author has killed a fruit fly directly above a comma.”

He has a point—many people aren’t quite sure when and where to use the mark, so the easiest thing to do is to avoid it altogether. But I’m more apt to agree with President Lincoln: a semicolon can be useful, particularly when you have two closely related sentences and you don’t want to put a full stop (i.e., a period) between them.

I recently edited an article on Commonwealth’s giving back programs for the Commonwealth Business Review in which I purposely changed a period to a semicolon because the second sentence supported the first:

  • Nick Botelho, team lead, transfer of assets, will be taking the lead on Commonwealth’s weeklong campaign to raise awareness and necessary dollars in support of [Autism Speaks: Light It Up Blue]; he has big plans for a 50/50 raffle, including tickets to some favorite Boston sporting events.

Originally, “he has big plans for . . .” was the beginning of a new sentence, but it is so closely related to the statement about raising “necessary dollars” that I felt it needed to remain part of this thought.

When to Use Commas, Colons, Semicolons, and Dashes

Knowing which punctuation to apply within sentences can be confusing. But rules are important and made to be followed, especially in academic writing. Putting a comma between two independent clauses will confuse your readers and make your work frustrating to read.

On the other hand, a well-placed semi-colon can add nuance and subtlety to any kind of writing. Keep the following rules in mind when choosing to use a comma (,), colon (:), semicolon (;), or dash (—).

When to Use a Comma

Commas are the most frequently used (and abused) punctuation mark in most kinds of writing. The reason for this is that they have so many uses and so many rules—it can be hard to keep track of them all. Let’s take a look at just a few of the comma’s crucial functions and discuss when to choose a comma over another similar punctuation mark.

To list items or short phrases:

I bought bread, cheese, and pickles at the grocery store

To separate long independent clauses when conjunctions connect them:

Astronomers have known about the positions of stars for centuries, but they didn’t understand that the earth revolves around the sun

After an introductory phrase:

In preparation for the next convention, the representatives studied up on the most important issues

To separate a parenthetical phrase or interrupter:

All doctors, if they care about their patients, are concerned with good office hygiene

Common Comma Mistakes

Comma splice. Do NOT use a comma to divide two independent clauses without a conjunction

Incorrect: Thousands of protesters showed up on the streets, they were shouting and carrying large posters

Correct: Thousands of protesters showed up on the streets; they were shouting and carrying large posters

Combining lengthy phrases. Using commas with compound sentences or to separate clauses with other commas can cause confusion. Use a semicolon

Incorrect: Some useful subjects are English, which is an international language, math, which is used in all domains of sciences and social sciences, and philosophy, which underpins many other areas of study

Correct: Some useful subjects are English, which is an international language; math, which is used in all sciences and social sciences; and philosophy, which underpins many other areas of study

When to Use a Colon

A colon is used to make lists and tell the reader, “This is what I mean.” The colon should not be used often in most kinds of writing unless there are extensive lists involved. The rules of the colon are strict but fairly easy to remember.

To introduce an item or series of items:

Humans use five major senses: sight, hearing, smell, taste, and touch

To separate independent clauses when the second clause/sentence illustrates, explains, paraphrases, or expands on the first:

Martha realized that her worst fear was coming true: her son was being sent to war

*The information after the colon explains Martha’s fear in the form of an independent clause.

To follow the salutation in a business letter or more formal letter:

To the Central Valley Committee Chairman:

More Tips For Using Colons

Do not capitalize the first word after the colon unless it is a proper noun, is part of a quote, or is the first in a series of sentences:

Incorrect: I have three desires: To eat, sleep, and work

Correct: I have three desires: to eat, sleep, and work

When a quotation contains multiple sentences, many writers prefer to introduce it with a colon rather than a comma:

In Chapter 3, the author explains his theory: “Dogs have dreams, but they don’t dream as humans do. Their dreams reflect a primal desire for pleasure, whereas humans are preoccupied with the ego and self-image. This is equally true in wakefulness and sleep.”

A complete sentence after the colon is not necessary—a word or phrase is fine

There is one mantra that can sum up our position towards climate change: urgent action

Common Colon Mistakes

Separating two clauses that have equal rank or unrelated information:

Incorrect: Sarah and her friends loved spending time on the mountain: nature always held a special meaning for them

Correct: Sarah and her friends loved spending time on the mountain; nature always held a special meaning for them

(*Use a period if the clauses are not at all related. Use a semi-colon if the information in the second clause is somewhat related but does not illustrate, explain, or paraphrase the first clause.)

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Overusing the colon:

The colon is a powerful punctuation mark and should be used sparingly. Think of it as a stop sign that calls readers’ attention and says, “Hey! Pay attention to this. This is important.” If there are too many stop signs on a street, you won’t be able to drive very smoothly or quickly. This is the same effect colons can have upon readers.

Because colons are so attention-grabbing, they can clearly indicate which information is important. For this reason, many authors use colons to introduce their main argument or supporting evidence.

When to Use a Semicolon

SAT Writing: Commas, Dashes, and Colons

In this chapter, we'll go over all the rules you need to know for each punctuation mark and give you examples and exercises that cover the full range of ways they can be tested. Just so we're on the same page, we'll first review the semicolon (covered in the Run-ons chapter).

The Semicolon

A semicolon is used to join two independent clauses.


  • I love the game of basketball; however, I don't play it myself.
  • The tribe was left without food for weeks; the members had no choice but to resort to cannibalism.
  • Bats are nocturnal creatures; they come out only during the night.

Anytime a semicolon isn't being used for this purpose, it's incorrect. The SAT loves to use semicolons to do dirty things they're not supposed to:

Example 1
Wrong: The platter was filled with berries, crackers; and cheese.
Correct: The platter was filled with berries, crackers, and cheese.
Example 2
Wrong: Ready for the journey of a lifetime; the boy hopped on the spaceship.
Correct: Ready for the journey of a lifetime, the boy hopped on the spaceship.

The Comma

Of all the punctuation marks, the comma has the most uses. We'll only go through the ones that are tested.

1. Use a comma after an introductory clause, phrase, or modifier

Example 3

Em dash

A pair of em dashes can be used in place of commas to enhance readability. Note, however, that dashes are always more emphatic than commas.


And yet, when the car was finally delivered⁠—nearly three months after it was ordered⁠—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell.

A pair of em dashes can replace a pair of parentheses. Dashes are considered less formal than parentheses; they are also more intrusive. If you want to draw attention to the parenthetical content, use dashes. If you want to include the parenthetical content more subtly, use parentheses.

Note that when dashes are used in place of parentheses, surrounding punctuation should be omitted. Compare the following examples.


Upon discovering the errors (all 124 of them), the publisher immediately recalled the books.

Upon discovering the errors⁠—all 124 of them⁠—the publisher immediately recalled the books.

When used in place of parentheses at the end of a sentence, only a single dash is used.


After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction).

After three weeks on set, the cast was fed up with his direction⁠—or, rather, lack of direction.

The em dash can be used in place of a colon when you want to emphasize the conclusion of your sentence. The dash is less formal than the colon.


After months of deliberation, the jurors reached a unanimous verdict⁠—guilty.

The white sand, the warm water, the sparkling sun⁠—this is what brought them to Fiji.

Two em dashes can be used to indicate missing portions of a word, whether unknown or intentionally omitted.


Mr. J⁠—— testified that the defendant yelled, “Die, a⁠——,” before pulling the trigger.

From the faded and water-damaged note, we made out only this: “Was ne⁠——⁠y going to m⁠—— K⁠——, but now ——⁠t.”

When an entire word is missing, either two or three em dashes can be used. Whichever length you choose, use it consistently throughout your document. Surrounding punctuation should be placed as usual.

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The juvenile defendant, ———, was arraigned yesterday.

The em dash is typically used without spaces on either side, and that is the style used in this guide. Most newspapers, however, set the em dash off with a single space on each side.


Most newspapers — and all that follow AP style — insert a space before and after the em dash.

Many word processors will automatically insert an em dash when you type a pair of hyphens. Otherwise, look for an “insert symbol” command. If you are using a typewriter, a pair of hyphens is the closest you can get to an em dash.

A Quick Guide to Punctuation

Punctuation is the tool that allows us to organize our thoughts and make it easier to review and share our ideas. The standard English punctuation is as follows: period, comma, apostrophe, quotation, question, exclamation, brackets, braces, parenthesis, dash, hyphen, ellipsis, colon, semicolon. Below is an explanation of some punctuation that is commonly misused.

Comma ,

Commas are primarily used to aid in clarity and to join two independent clauses with a conjunction. They set off introductory phrases and set off series. They also are used to separate independent and dependent clauses. The Oxford comma is the inclusion of a comma before coordinating conjunction in a series.

I enjoyed the singers, and I loved the dancers.
At the beginning of the performance, two dancers appeared from behind the curtain.
Even though the auditorium was packed, the audience remained silent.

I had eggs, toast, and orange juice.

  • Commas can also be used to note an interjection in a sentence.
  • Example:
    The criminal said the judge was an idiot.
  • The criminal, said the judge, was an idiot.

The criminal is speaking in the first sentence. The judge is speaking in the second.

Apostrophe ‘

Apostrophes are used to mark possession and to mark contractions. They are also used to denote a quotation mark in material that is already being quoted.

It was James’ car that the drunk driver hit.

“James said, ‘If you come any closer I’ll call the police.'”

Quotation ” “

Quotation marks are used to inform a reader either of something that was spoken or something that is being directly copied from another work. Quotes should also be placed around a word if it is used in a specific context or otherwise bears special attention. In informal applications, quotations can also be used to denote something that is ironic.

Lydia said, “Is this my prom dress?”

Dr. Shruti claims, “The use of violence against women in India is on the rise.”

Question and Exclamation ? !

Question and exclamation marks are used to note interrogative and exclamatory sentences. Neither of these punctuation marks are commonly used in academic writing. In general, a writer should not be shouting at the reader in formal writing. The lack of conversation makes any question rhetorical, and revising the question in a statement would be the better course.

Hyphen –

Hyphens are most commonly used to pair compound words. Throw-away, high-speed-chase, merry-go-round, user-friendly

Dash –

Dashes are generally not in common use but denote a tangent within a thought. There are two kinds of dashes, an “en” dash and an “em” dash. En dashes essentially are the same glyph as hyphens but fill a different purpose. Em dashes are longer, an easy way to remember is that an en dash is the length of an “n” and an Em dash is the length of an “m”.

I think that my dog is a genius — but doesn’t everybody think their pet is?

Dashes are able to substitute for commas and semicolons in the right situation. They can replace commas to note non-essential information or semicolon to note an example. Despite, and because of this versatility dashes should not be frequently employed in your writing. The multitude of applications make dashes easy to overuse taking away from, rather than adding to clarity in your writing.

Note: Dashes can either connect to the surrounding words or be separated by a space, it is an issue of style, be sure to ask your professors if they have a preference.

Parenthesis (), Brackets [], Braces {}

Parenthesis note non-essential information that could be skipped without altering the meaning of a sentence. Brackets are most commonly employed in academic writing within a quotation where the writer is omitting or explaining something. In either case, the writer places a bracket within the quote [explains or places an ellipsis and] closes the bracket to continue the quote.

Braces are used quite rarely and are employed to essentially make a list within a list.

Cora (the woman who lives down the street from Jane) works as a paralegal.
Professor Brown claims, “She [the novel’s central character] is an example of a strong African-American woman.”

Before I go on vacation I need to pack my bags {clothes, toiletries and shoes}, unplug the TV, and close all of the windows.

Ellipsis …

Ellipsis marks the omission of a word or words. If the omission includes the end of a sentence the glyph has four dots (….) instead of three.

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Colon :

Colons make the statement: note what follows. Whatever information that follows the colon must, in some way, explain, prove, or describe what ever came before it.

To properly employ a colon, ensure that the clause that follows the mark is able to stand on its own (unless it is a list).

Because whatever comes before the colon must be a complete sentence, your writing after the colon is not required to be.

The Bridgekeeper asked me three questions: what is your name, what is your quest, what is your favorite color.

Semicolon ;

A semicolon can be used to join two related main clauses.

James Left a mess at his desk after he left work; Sarah had to clean it up.

Another way to employ a semicolon to join two related main clauses is to include a conjunctive adverb such as: however, moreover, nevertheless, furthermore, consequently, or thus. Conjunctive adverbs can also be used with a comma.

James left a mess at his desk after he left work; consequently, Sarah had to clean it up.

The simplest way to deal with two independent main clauses is to make two sentences. If the topic of the two sentences are not related, or if one (or both) of the sentences are already long, joining them could make the sentence too long and be a burden on the reader.

One of the most common applications of semicolons is as a substitute for commas in a list in which commas are required for the things listed.

It’s as easy as a,b,c; 1,2,3; doe, rae, mi.

Dashes, Colons, and Semicolons | The Writing Center | University of the South

Connecting Sentences: Dashes, Colons, and Semicolons

Download this handout here.


Dashes, colons, and semicolons connect two independent clasues that are related in thought. 

What can they do for my writing?

Essentially, semicolons, colons, and dashes offer you different ways to join your ideas together, and you can use them to adjust how you want your sentences to sound. A comma between two independent clauses creates a run-on sentence that doesn't give enough definition between your ideas, while a period between them sometimes distances them too much.

Connecting your clauses with a semi-colon might provide a pause that is just right, while a dash could make that pause more dramatic by highlighting the following clause, or a colon could signal that the second clause expands on the first.

But remember that when deciding whether to use a period or a semi-colon, a colon or a fash, it is more a stylistic/rhetorical choice than a choice of right or wrong. 

How do I use them properly?

1. Dashes

Quick Use: Use a dash to connect independent clauses or to inerrupt a main clause in a way that creates dramatic effect.

Semicolons, Colons, and Dashes


Punctuation marks: terribly powerful in the right hands. Punctuation marks are silent allies, and you can train yourself to exploit them as such. Punctuation marks do not just indicate sound patterns—they are symbols that clarify grammatical structure and sentence meaning. And, as I demonstrate in the writing of this paragraph, punctuation marks showcase your facility with the language. What follows are some basics about three of the most powerful and most commonly misused punctuation marks.

The Semicolon

The semicolon is often misused in technical writing; in fact, it is often confused with the colon. Grammatically, the semicolon almost always functions as an equal sign; it says that the two parts being joined are relatively equal in their length and have the same grammatical structure.

Also, the semicolon helps you to link two things whose interdependancy you wish to establish. The sentence parts on either side of the semicolon tend to “depend on each other” for complete meaning. Use the semicolon when you wish to create or emphasize a generally equal or even interdependent relationship between two things.

Note the interdependent relationship of the two sentence parts linked by the semicolon in this example:

The sonde presently used is located in the center of the borehole; this location enables the engineer to reduce microphonics and standoff sensitivity.

Here, we see how the second half of the sentence helps to explain a key detail (the sonde location) of the first half. The semicolon, along with the repetition of the word “location,” helps to draw our attention to the explanation.

The semicolon is also handy for linking a series of parallel items that could otherwise be confused with each other. One savvy student used the semicolon in a job description on her resume as follows:

As an engineering assistant, I had a variety of duties: participating in pressure ventilation surveys; drafting, surveying, and data compilation; acting as a company representative during a roof-bolt pull test.

The Colon

The colon: well-loved but, oh, so misunderstood. The colon is not just used to introduce a list; it is far more flexible. The colon can be used after the first word of a sentence or just before the final word of a sentence. The colon can also be used to introduce a grammatically independent sentence. Thus, I call it the most powerful of punctuation marks.

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