The toughest thing about parentheses, ( ) , may be knowing the difference between this plural form and the singular, parenthesis (though that form less often also refers to the pair). But what precisely do they do?
Parentheses indicate a hiccup—not literally, of course, but an interruption in a sentence. A piece of information not closely related to the other content, but in the eyes of the author, necessary, should be enclosed by parentheses.
Sometimes there’s a fine line between content that is closely related and that which isn’t. Often the author’s judgment makes the determination. If he deems the material to be closely related, he can choose to use em dashes instead, or even commas.
In the first paragraph, for example, I could have written the last sentence like this: A piece of information not closely related to the other content (but in the eyes of the author, necessary) should be enclosed by parentheses.
Another viable choice would be the following: A piece of information not closely related to the other content—but in the eyes of the author, necessary—should be enclosed by parentheses.
In other words, the punctuation the author chooses has a lot to do with how he wants the sentence read. If he wants to distance the parenthetical material from the rest of the sentence, parentheses are best. Em dashes bring the material closer, and commas, closest of all, with only a brief pause intended, not the hiccup of the parentheses. 😉
Brackets, [ ] , also called square brackets, are used to enclose content that has been added to the rest of the text. This information most often has been inserted by someone other than the original author. For example, an article, when quoting a source, may need to clarify a pronoun. Therefore the writer inserts a noun to replace the pronoun and does so by placing the added word in brackets.
Here’s an example:
After the game Titan coach Anthony Davis said, “They [the Sonora Spartans] were a tough team, well-prepared for the game.”
Sometimes brackets are used for an editorial note such as “sic” (to indicate an error or an oddity). Below is an example of this use.
The synopsis began with this line: “The boys should have come hear [sic] at once.”
Of course there are specialty uses for both these marks, but this information gives you the most common use of each.