on Writing Forward:
Parentheses are among the most useful and versatile punctuation marks in the English language. They can be used effectively in both formal and casual writing, and the rules surrounding parentheses allow writers to use them for a variety of purposes.
They just might be my favorite punctuation marks, simply because they provide a clear way for writers to issue an aside.
But parentheses should be used conservatively and with discretion. Today we’ll look at the many ways in which these punctuation marks come in handy and explore the rules for usage and formatting.