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Some of us have used round and square brackets interchangeably over the years because we didn’t know they are not the same, but they are, actually. We learn every day, so this could be a new knowledge we could apply to make us look smarter—and who doesn’t want to anyway?

These brackets have different uses which are simple to learn and remember. Let’s get to them right away.

Round brackets ( )
These are also known as parentheses (especially in American English). We use them for the following:
i. To enclose extra pieces of information that are not crucial to the rest of the sentence. This implies that when they are removed, the meaning of the sentence is not affected.
Examples:
1. Oceans (around the world) are beautiful when you watch them glow at sunset.
2. Assassin (from Arabic hashishiyyin) is a scary word for anyone who knows what it means.

ii. To express personal comments or afterthoughts. When you write and you have a personal opinion to add, use a round bracket.
Examples:
1. It is a beautiful day to start the project(but tomorrow would have been better).
2. I will make sure he is prosecuted and jailed (though I won’t be the judge).

iii. To add an acronym after the name of an organisation, position, etc.
Examples:
1. He served as the Director of Military Intelligence (DMI) in the First Republic.
2. The Human Resources Manager (HRM) is a pivotal member of the board.

*Note that you should avoid using organisation, etc. names and acronyms together after the first time in writing, use either of them subsequently (acronyms generally preferred).

iv. To indicate that a word could be singular or plural.
Examples:
1. The player(s) might be attacked by fans after the match.
2. If we consider the alternative(s), we could discover simpler ways(s) of starting the research.


Square brackets [ ]
Square brackets are also simply called brackets (especially in American English). These are their uses:
i. The main function of square brackets is to enclose words that are added by someone other than the writer. These additions are mainly for clarity and do not affect the meaning of the expressions if removed.
Examples:
i. The mother [the one with blue eyes] believed that the training was a charade.
ii. She [Alinko’s wife] greeted us cordially, grinning from ear to ear.

ii. To modify or correct what someone has written.
Examples:
1. I shook hands with [the] president of the association.
2. He knew he can [could] do it.

Note: The full stop appears after the last bracket of round or square brackets when they are used at the end of a sentence. But if the bracketed information is a whole sentence, that is how it should be treated (with a full stop inside the bracket). However, this is rarely used.
Examples
1. The last lap was quite tiring (as usual).
2. The army staged an abortive coup against hers [her].
3. Sometimes we fail to realise how intelligent we are. (We are better than we sometimes think.)

Beautiful

Nice.

Noted