BracketsThe difference in grammar (I know the difference between them in math.ha ha).
Parentheses are usually used in the citation of text with a work, such as citing a line, page number, or author. They are usually at the end of the quote. Brackets are used to alter quoted text. It shows the reader that the alteration has been made. Usually used to change verb tenses or modify nouns, such as instead of him or her, a proper noun is used. For example, in an interview, if a person misused a verb tense or noun, you can't simply change it still quote it as their word. However you can put the correction in brackets so the reader will be aware that is where you changed it.
