Avoid using too many brackets in text and make sure they’re always closed. If the whole statement is within brackets the final full stop should be inside them.

Use round brackets when adding supplementary information to the text.

The arithmetic was wrong (which is unheard of)
The Royal Society for the Protection of Animals (RSPCA)
(The Authority has the final say on these.)

Use square brackets when adding comments or corrections.

The judge stated: “You [Mr Sykes] have suffered.”
On Twitter she said: “The statistecs [sic] seemed wrong”