While square brackets are used to make a quoted text more readable or a faster read, round brackets or parentheses are generally used to add details. Brackets that are round are also used to show that an item can be either singular or plural, as in the following: We picnicked beneath the tree(s).
If information is added to round brackets at the end of a phrase, the punctuation is included after the bracket, as in – Everyone applauded his efforts (even his rivals).
However, do not make a practice to use lots of round brackets as they do not enhance the format of a sentence. You can also use dashes, if necessary, or commas.
Using Square Brackets
When it comes to square brackets, again, these grammatical aids are used to make text better understood. For example, the following quote is better digested by using a square bracket: “It [butter] is a fatty substance that is yellow in color and used as a spread or for cooking.”
In addition, square brackets can be employed for enclosing the term “sic”. This term is used to show that a grammar mistake was written in the text by the quoted author. For example, “sic” is used in the following text:
His request for a “small compliment [sic] of men” was refused. The word “compliment” should be “complement.”
Square brackets are also used to include ellipsis. The use of ellipsis indicates that the text has been removed from a quote. Ellipsis, or “. . .” can be used alone as well. For example, the following quote features a bracketed ellipsis:
“Be who you are [. . .] because those who mind don’t matter, and those who matter don’t’ mind.” –Bernard M. Baruch.
The part of the quote that was omitted was “and say what you feel.”
Brackets that are square, when used for quotes, are also included to add missing words, such as – “That is [an] insightful comment.”
Use brackets that are square in non-quoted text, to provide an authorial or editorial comment – They will not attend the conference [my emphasis].
You can also use square brackets to modify a direct quotation, or another person’s words, as in the following:
“She “love[s] to knit.” The original words were “She loves knitting.”
Once you know why brackets you are used—square or round—you can clarify your text or content, and make any technical writing or reportorial content easier to comprehend.