Using punctuation effectively means that your reader can make sense of your writing, It can also help create a particular effect to give your writing depth.
Part of English LanguageSpelling, punctuation and grammar
These are sometimes called 'parentheses' and can be used to add extra information from the writer, or add description to a sentence:
The boy (a young boy who had never left home) looked terribly pale.
If you are using brackets towards the end of a sentence, the full stop to complete the sentence goes outside of the brackets:
Neharika wore the blue shoes (her sister, Amrita, had already chosen the red ones).