Brackets Or Parentheses In Quotes & Sayings

A few words which he wanted to emphasize were put into brackets or set off by quotation marks. My first impulse was to point out to him that it was ridiculous to put slang words and expressions between quotation marks, for that prevents them from entering the language. But I decided not to. When I received his letters, his parentheses made me shudder. At first, it was a shudder of slight shame, disagreeable. Later (and now, when I reread them) the shudder was the same, but I know, by some indefinable, imperceptible change, that it is a shudder of love- it is both poignant and delightful, perhaps because of the memory of the word shame that accompanied it in the beginning. Those parentheses and quotation marks are the flaw on the hip, the beauty mark on the thigh whereby my friend showed that he was himself, irreplaceable, and that he was wounded. — Jean Genet

Brackets come in various shapes, types and names:
1 round brackets (which we call brackets, and the Americans call parentheses)
2 square brackets [which we call square brackets, and the Americans call brackets] — Lynne Truss