Dashes, Parentheses, Commas, and Colons
While some rules related to grammar are steadfast, some seem to be more optional in nature. When it comes to choosing from among dashes, parentheses, commas, and colons — punctuation marks that often seem to accomplish something similar — most writers simply wing it rather than research which would actually be most appropriate to use in a particular sentence.
Let’s start with a definition from Merriam-Webster for each of these common punctuation marks. A dash indicates “a break in the thought or structure of a sentence.” Parentheses are used to “enclose a parenthetical expression.” A comma is used “as a mark of separation” within a sentence. And a colon is “used chiefly to direct attention to matter (such as a list, explanation, quotation, or amplification) that follows.”
Multiple types of dashes exist and are used in different ways. They are also commonly confused with hyphens. To learn more about which type of dash to use when — and when to use a hyphen instead — see “A Beginner’s Guide to Em Dashes, En Dashes, and Hyphens” by Lynda Dietz. When considering whether to introduce something with a dash, it helps to think of a dash as a bit of a drama queen compared with the more utilitarian parentheses, comma, or colon. Dashes are preferred by many writers for many reasons, but they can be overused. They’re best saved to present information that are just as dramatic as they are, though of course there are exceptions to this rule. Sometimes when the information to be included within two dashes, parentheses, or commas contains commas itself, the use of dashes or parentheses helps avoid confusion. If the extra information is not exactly exciting, parentheses might be the better choice.
Parentheses seem to be a much more ordinary, almost skimmed-over, punctuation mark when compared with dashes. In most cases, the information they contain could be deleted without impacting the meaning or tone of a sentence. In the above paragraph, the one sentence that uses dashes could be rewritten using parentheses to read: “To learn more about which type of dash to use when (and when to use a hyphen instead) see ‘A Beginner’s Guide to Em Dashes, En Dashes, and Hyphens’ by Lynda Dietz.” The original version makes the reference to “when to use a hyphen instead” stand out rather than seem almost dispensable. Again, parentheses are most helpful when more mundane information is being presented, especially when the information presented includes commas.
Commas are so common that they, too, are often skimmed over. When it comes to presenting extra information within a sentence, however, they provide a very straightforward option that does not interrupt the flow of a sentence as much as parentheses or dashes might. The one exception, as noted above, is when the extra information contains commas. The use of commas to frame such information might make a sentence more difficult to read. Consider this sentence: “All her siblings, including her oldest brother, Steve, and her younger sisters, Ellen, Eve, and Edna, visited while she was in town.” Using either dashes or parentheses might be a better choice: “All her siblings — including her oldest brother, Steve, and her younger sisters, Ellen, Eve, and Edna — visited while she was in town.” “All her siblings (including her oldest brother, Steve, and her younger sisters, Ellen, Eve, and Edna) visited while she was in town.” Since the extra information provided in this sentence isn’t exactly exciting, parentheses may be the best option.
As its definition states, colons are “used chiefly to direct attention to matter (such as a list, explanation, quotation, or amplification) that follows.” I noted in “3 Free Online Resources to Help You Improve Your Grammar” that Grammar Girl is one of my favorite websites for helpful tips related to writing. In her piece on colons, Grammar Girl offers up a nifty trick: “Most of the time, if you can replace a colon with the words ‘namely,’ or ‘it is,’ or ‘they are,’ then the colon is the right choice.” For example, in the sentence immediately preceding this one, the word “namely” could replace the colon, which indicates that the use of a colon is correct.
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I write fiction, poetry, and nonfiction when I’m not working as a copy editor. Author of the novel One Sister’s Song.