If you need to put something parenthetical inside a sentence or phrase that is already in parentheses, use brackets:

The name Unabomber comes from the designation that the FBI used for the case (UNABOM [an acronym for “UNiversity and Airline BOMber”]) before it was solved.

You can also use brackets to add information within a quotation or to clarify something that might be confusing or ungrammatical when taken out of its original context:

Learn more about using brackets when modifying quotations.