Parentheses

Figure 1. An opening and closing parentheses.

Parentheses can do more than make smiley faces :) and sad faces :( like these! They serve an important function in formal writing as well.

Parentheses are used to set off information in a sentence that is important but not really a part of the main message. It’s important to remember that your sentence should make sense if you eliminate the parentheses and all that is contained between them.

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 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.

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).

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

Figure 2. An opening and closing bracket.

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 him today. I had a really great time with him. He was a lot taller than expected, though.”

Maybe you don’t want to use this whole passage or want to add clarity.

You might write:

“I finally got to meet [Trent] today.” Here, the brackets replace him and explain who the word him references.

When you can, avoid brackets, however.

Instead of writing “[Trent] was a lot taller than expected,” you might write:

Trent is “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, 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

Figure 3. An ellipsis.

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.

Here is another example, with an ellipsis followed by a comma:

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!)