Bracket Your Parentheses
Q. When should I use brackets and when parentheses in writing reports?
A. Brackets are the square enclosure marks inserted by a second writer to signal corrections, interposed comments, explanatory notes, or translations that were not in the original text.
Parentheses are the rounded enclosure marks used primarily to signal definitions, examples, and other remarks by the original writer of the text. Use parentheses sparingly. (Too many of them indicate that you are getting wordy and drifting away from the main point; you certainly don't want to be guilty of that.)
Helpful Hint: Enclosing the word sic, meaning thus, in brackets [sic] is a way of signaling to the reader, "Don't blame me for the misspelling or factual error; that's the way I found it in the original."