Parentheses

Parentheses are most often used to identify material that acts as an aside (such as this brief comment) or to add incidental information.

Other punctuation marks used alongside parentheses need to take into account their context. If the parentheses enclose a full sentence beginning with a capital letter, then the end punctuation for the sentence falls inside the parentheses. For example:

Typically, suppliers specify air to cloth ratios of 6:1 or higher. (However, ratios of 4:1 should be used for applications involving silica or feldspathic minerals.)

If the parentheses indicate a citation at the end of a sentence, then the sentence’s end punctuation comes after the parentheses are closed:

In a study comparing three different building types, respirable dust concentrations were significantly lower in the open-structure building (Hugh et al., 2005).

Finally, if the parentheses appear in the midst of a sentence (as in this example), then any necessary punctuation (such as the comma that appeared just a few words ago) is delayed until the parentheses are closed.

You can also use parentheses to provide acronyms (or full names for acronyms). For example, “We use the MLA (Modern Language Association) style guide here” or “The Modern Language Association (MLA) style guide is my favorite to use.”

Remember, parentheses always appear in pairs. If you open a parenthesis, you need another to close it!

Brackets

Brackets are a fairly uncommon punctuation mark. Their main use is in quotations: they can be used to clarify quotes. For example, say you want to quote the following passage:

“I finally got to meet Trent today. I had a really great time with him. He was a lot taller than expected, though.”

However, you only want to relay the fact that Trent was taller than the speaker expected him to be. In order to do this, you would write the following: “[Trent] was a lot taller than expected.”

The brackets let the reader know that while the word Trent wasn’t in the original quote, his name was implied there. When using brackets, you need to be careful not to change the original meaning of the quote.

Another use of brackets is when there is a spelling or informational error in the original quote. For example, “Gabriel sat down on the river bank to fed [sic] the ducks.”  (The term sic means that the typo was in the original source of this quote.)

Ellipses

An ellipsis (plural ellipses) is a series of three periods, as you can see in the icon to the right.

As with most punctuation marks, there is some contention about its usage. The main point of contention is whether or not there should be a space between the periods (. . .) or not (…). MLA, APA, and Chicago, the most common style guides for students, support having spaces between the periods. Others you may encounter, such as in journalism, may not.

Quotes

Like the brackets we just learned about, you will primarily see ellipses used in quotes. They indicate a missing portion in a quote. Look at the following quote for an example:

Camarasaurus, with its more mechanically efficient skull, was capable of generating much stronger bite forces than Diplodocus. This suggests that Camarasaurus was capable of chomping through tougher plant material than Diplodocus, and was perhaps even capable of a greater degree of oral processing before digestion. This actually ties in nicely with previous hypotheses of different diets for each, which were based on apparent feeding heights and inferences made from wear marks on their fossilized teeth.

Diplodocus seems to have been well-adapted, despite its weaker skull, to a form of feeding known as branch stripping, where leaves are plucked from branches as the teeth are dragged along them. The increased flexibility of the neck of Diplodocus compared to other sauropods seems to support this too.

It’s a lengthy quote, and it contains more information than you want to include. Here’s how to cut it down:

Camarasaurus, with its more mechanically efficient skull, was capable of generating much stronger bite forces than Diplodocus. This suggests that Camarasaurus was capable of chomping through tougher plant material than Diplodocus. . . . This actually ties in nicely with previous hypotheses of different diets for each, which were based on apparent feeding heights and inferences made from wear marks on their fossilized teeth.

Diplodocus seems to have been well-adapted . . . to a form of feeding known as branch stripping, where leaves are plucked from branches as the teeth are dragged along them.

In the block quote above, you can see that the first ellipsis appears to have four dots. (“They are instantly recognized by their long, sweeping necks and whiplashed tails. . . .”) However, this is just a period followed by an ellipsis. This is because ellipses do not remove punctuation marks when the original punctuation still is in use; they are instead used in conjunction with original punctuation. This is true for all punctuation marks, including periods, commas, semi-colons, question marks, and exclamation points.

By looking at two sympatric species (those that lived together) from the fossil graveyards of the Late Jurassic of North America . . . , [David Button] tried to work out what the major dietary differences were between sauropod dinosaurs, based on their anatomy.

One of the best ways to check yourself is to take out the ellipsis. If the sentence or paragraph is still correctly punctuated, you’ve used the ellipsis correctly. (Just remember to put it back in!)

The ellipsis can also indicate . . . a pause. This use is typically informal, and is only be used in casual correspondence (e.g., emails to friends, posts on social media, texting) or in literature. Because this use occurs in literature, you may find yourself quoting a passage that already has an ellipsis in it. For example, look at this passage spoken by Lady Bracknell, in The Importance of Being Ernest.

Well, I must say, Algernon, that I think it is high time that Mr. Bunbury made up his mind whether he was going to live or to die.  This shilly-shallying with the question is absurd.  Nor do I in any way approve of the modern sympathy with invalids.  I consider it morbid.  Illness of any kind is hardly a thing to be encouraged in others.  Health is the primary duty of life.  I am always telling that to your poor uncle, but he never seems to take much notice . . . as far as any improvement in his ailment goes.  I should be much obliged if you would ask Mr. Bunbury, from me, to be kind enough not to have a relapse on Saturday, for I rely on you to arrange my music for me.  It is my last reception, and one wants something that will encourage conversation, particularly at the end of the season when every one has practically said whatever they had to say, which, in most cases, was probably not much.

If you were to quote the passage, it may appear that something has been removed from the quote. So how can we indicate that this is not the case? If you think back to the bracket rules we just discussed, you may remember that [sic] can be used to show that an error was in the original. In a similar practice, we can enclose the ellipsis in brackets to show it appeared in the original work:

Well, I must say, Algernon, that I think it is high time that Mr. Bunbury made up his mind whether he was going to live or to die.  This shilly-shallying with the question is absurd.  Nor do I in any way approve of the modern sympathy with invalids.  I consider it morbid.  Illness of any kind is hardly a thing to be encouraged in others.  Health is the primary duty of life.  I am always telling that to your poor uncle, but he never seems to take much notice [. . .] as far as any improvement in his ailment goes.  I should be much obliged if you would ask Mr. Bunbury, from me, to be kind enough not to have a relapse on Saturday, for I rely on you to arrange my music for me.  It is my last reception, and one wants something that will encourage conversation, particularly at the end of the season when every one has practically said whatever they had to say, which, in most cases, was probably not much.