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Using Commas, Colons, Semicolons, Em-Dashes, En-Dashes, and 3-Em Dashes Correctly


The word "punctuation" strikes academic fear into the hearts of many English speakers around the world. From commas to periods and colons to interrobangs, correctly punctuating text can take quite a bit of effort and understanding. This article will focus on six specific punctuation marks: comma, colon, semicolon, em dash, en dash, and 3-em dash. These types of punctuation are all used to divide sentences in ways that increase clarity and emphasis on what is essential and what is ancillary.

Before going into the specifics of usage for each type of punctuation, it is important to note that there is a time and a place for using punctuation like this. Academic, legal, and scientific writing, for example, rely heavily on proper punctuation use to ensure clarity of often complicated subjects and ideas. Without commas, semicolons, etc., many specific pieces of information would not be understandable or may even be presented incorrectly, causing confusion in ways that could win or lose a court case or cause errors in scientific and medical applications. Punctuation use in social media and texting settings isn't as necessary. When texting, for example, much of the communication is in shorthand or small, simple thoughts. Using a semicolon in a text message generally would seem out of place to the recipient. The key is to be conscious of your audience and the platform on which you are communicating.


Commas are some of the most difficult punctuation marks to master. They have many different uses that vary according to the intent of a sentence or clause and the user. In addition, commas have a lot of power. They can change the meaning of a sentence even to the point of being the opposite of the intended meaning. Commas don't even have to be present to make an impact; simply their absence can have a big effect on the meaning of a sentence. On top of the grammatical aspects of commas, there are also stylistic and mechanical conventions to consider.

The first type of use is one that most of us are familiar with: the listing comma. When writing out a list of three or more items in a sentence, the comma separates each item. This helps to distinguish between each item in the list and make it clear what the writer is referring to. Here is also where the comma gets some drama and attention. The all-famous Oxford comma, or serial comma as it is also called, presents as the final comma in the list, coming just after the last item in the list and before the conjunction. Some people love the Oxford comma and swear by its use because of its ability to ensure clarity in thought. Others, however, have a severe disdain for the Oxford comma, saying that it is unnecessary and pretentious. They key to good comma usage in this case is to be consistent throughout the document (maintaining style) and ensuring that you are managing clarity in your choice.

Another comma use is separating multiple adjectives that apply to the same noun. Some adjectives are combined to describe a noun, such as in "a dull blue handle." Dull and blue are not individually describing the handle; rather, dull and blue are chained together to jointly describe the handle's color. Change the phrase just slightly, though, and you get two adjectives that individually describe a noun, as in "loud, joyous laughter." In this example, the laughter is both joyous and loud.

Lastly, one key use of the comma is to separate nonessential and nonrestrictive information in a sentence. A pair of commas in the middle of a sentence sets off clauses, phrases, and words that are not essential to the meaning of the sentence. Use one comma before to indicate the beginning of the phrase and one at the end. According to the Purdue Online Writing Lab, here are some good questions to help you identify if a phrase is nonessential:

  • If you leave out the clause, phrase, or word, does the sentence still make sense?
  • Does the clause, phrase, or word interrupt the flow of words in the original sentence?
  • If you move the element to a different position in the sentence, does the sentence still make sense?

If you answer yes to any of those questions, then the phrase is nonessential. Essential clauses are sometimes identified by the use of the word "that." Nonessential clauses of a similar type will use the word "which." Keep those in mind as you try to determine whether you need to use a comma before the clause.


In grammar, colons are relatively simple to use. Designed as two dots placed one on top of the other, its appearance is a sort of fence between words, phrases, or sentences. In a sense, they allow a reader to "see" from one side of a sentence to another. Their most essential function, however, is to set off a list that is not incorporated into a sentence. Here are three examples of list items: item 1, item 2, and item 3. This also applies if you were to have a bulleted list after a sentence introducing those list items.

Another interesting use of a colon is to emphasize a word or phrase at the end of a sentence. For example, "He had one reason for going to Atlanta: love." Taking this a step further, you can also use a colon to separate two independent clauses. The semicolon and the em dash, as you will read later on, have a similar function.

The following examples illustrate these uses of colons:

"Three weeks into the vacation, the couple decided there was only one thing to do: move to paradise."
"She had traveled around the world in just 60 days: there would never be an opportunity like that again."


Often used as half of a winky face in text messages, emails, and social media posts, semicolons can be a bit playful even outside of popular emoticons. Semicolons are most often used to connect two independent clauses. Independent clauses are clauses that can stand alone as complete sentences. The semicolon essentially takes place of a conjunction like and, but, or, and yet. It also takes the place of a period in distinguishing between the two complete sentences. This only applies if the two sentences are connected in thought. See the following examples:

"I went to the river to fish; my dog begged to join me."
"You are permitted to spend your lunch hour outside; you must remain on the premises."

This use also is applied when two independent clauses are linked by a transitional expression. For example, one could write, "We decided to have lunch at Marie's house; however, Marie was out of town that day."

Finally, semicolons play an important role in lists there are multiple sub-lists. When a list has an embedded sub-list, the semicolon should be used to separate all list items and list groups. For example, "In the grocery store, get pickles, mustard, and relish; bread and hot dog buns; paper plates; forks, knives, and spoons; and milk."

Em Dash, En Dash, and 3-Em Dash

Em dashes, en dashes, and 3-em dashes are very versatile tools in writing. These dashes are named according to their width. The em dash is about the width of the capital letter M, and the en dash is about the width of the capital letter N. The 3-em dash is the width of three em dashes in a row.

The em dash (—) is used to set off parenthetical information in a sentence. Using em dashes instead of parentheses puts the focus on the information between the em dashes. You can also use an em dash to set off an appositive that contains commas. An appositive is extra information added to a sentence for clarification. While appositives are often set apart by commas, an em dash can improve clarity when the appositive has commas already in it.

"The three of us—Mary, Joe, and I—went to the movies yesterday."

The en dash (–) is used with numbers and shows a range, such as in page numbers, dates, and temperature, when the number or word is not preceded by "from" or "between." For example, "The bookstore is open 9–5pm today." You would not write, "The store is open from Monday–Friday." Instead, you would write, "The store is open from Monday to Friday."

The 3-em dash (———) is used in bibliographies when an author's name is repeated. In the Chicago Manual of Style format, bibliographies only list the same author's name once in the references list, as below:

Tarn, William. Alexander the Great: Narrative. Cambridge: Oxford University Press. 1951.
———. Alexander the Great: Sources and Studies. Cambridge: Oxford University Press. 1948.
———. Hellenistic Military and Naval Developments. Chicago: Ares Press. 1930.

Punctuation can be complicated the deeper you go into writing. With practice, some of the more obscure uses of commas, colons, semicolons, and various dashes will become easier. To start, remember these basic rules, and you will be able to communicate your ideas clearly and with style.

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