Brackets – What’s The Difference Between Them All?

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In mathematics as well as in coding or writing, these punctuation marks are used for different reasons and indications. However, there are so many different brackets out there, it’s hard to know which to use when and in which environment.


Here on, we have taken a closer look at all kinds of brackets you may come across and how to use those that are relevant for any kind of fictional, formal and informal writing.


The Different Kinds Of Brackets

In general, brackets refer to a pair of punctuation marks that either match or set apart a string of text or numbers form the rest of a text or formula. While slashes and backslashes are sometimes also used as some kind of brackets, we will have a look at the four “main kinds” of brackets you encounter almost on a daily basis and in many different fields.


Round Brackets or Parentheses – ( )

The parentheses (in modern British English referred to as simply brackets), is the most common form of brackets, especially in writing. They are used in formal as well as informal writing for different purposes. For example:

  • Clarify information in a given text:
    • Maria (who was late for school) got scolded by the teacher.
  • Set information apart from the rest of the text
    • The term pit bull (usually a mixed breed of bulldogs and terriers) often refers to dogs of the same build rather than a pure bred pit bull.
  • Indicate singular/plural or gender
    • I don’t know if (s)he would be happy to her that.


Next to writing, parentheses is also used in other fields such as:

  • programming; denoting an argument or as a fundamental construct of a coding language (cf. LISP)
    • (incf x)
  • mathematics; denoting that certain operations take place first or setting apart arguments from functions
    • (2 + 5) × 5
    • f(x)


In some circumstances, an unpaired parenthesis can occur as well. This is especially common in certain forms of lists that use lowercase roman letters such as:

a) item 1
b) item 2


Square Brackets or Crotchets – [ ]

When using the term brackets in American English, it mostly refers to the square brackets. It serves several different functions that differ from the usage of the parentheses. Some of them include:

  • Inserting information to a text
    • The famous Battle of Hastings [October 14, 1066] was fought between the Norman-French army and the English army.
  • Marking omitted material within a text
    • “Some who have read the book […] have found it boring, absurd, or contemptible, and I have no cause to complain, since I have similar opinions of their works, or of the kinds of writing that they evidently prefer.” – J.R.R. Tolkien
  • Adding something to or modifying a quote
    • “The Dark Lord has Nine. But we have One, mightier than they: the White Rider [Gandalf the White]. He has passed through the fire and the abyss, and they shall fear him. We will go where he leads.” – J.R.R. Tolkien


Furthermore, the square brackets are used in other fields and for other purposes as well:

  • proofreading; to insert comments or indicate changes applied to a sentence
  • mathematics; notation of intervals and other functions
    • [a, +∞]
  • chemistry; representing the concentration of a chemical substance
  • programming; indicating arrays
    • int anArrayName[10];
  • linguistics, Phonetic transcriptions
    • “little” [ˈlɪɾɫ̩]


Curly Brackets or Braces – { }

Not commonly used in either formal or informal writing, the curly brackets still occur in writing poetry and music. In either usage, they mark either repeated or joined lines.


Curly brackets are far more common on other fields like:

  • mathematics; delimiting sets
    • {5,10,15}
  • programming; enclosing groups of statements
    • switch (c) { case ‘a’: alert(); break; case ‘q’: quit(); break; }


Angle Brackets or Chevrons – < >

The main usages of the angle brackets occur in other fields. A selection of those includes:

  • mathematics; inner product between elements
    • <a|b>
  • programming; insertion of code
    • <a href=”>Text</a>
  • linguistics; marking graphemes or orthography
    • [ˈlɪɾɫ̩] <little>


Unpaired, symbols similar to the angle brackets are also frequently used. Take, for example the greater-than ( > ) and lesser-than ( < ) symbols. In some languages, the usage of double pairs of symbols that look like angle brackets are used instead of quotation marks («, »).


Even More Brackets

In different languages of the world or for different mathematical, physical or linguistic functions, even more kinds of brackets are used. However, since they are widely unknown in the everyday usage of most people and not used in our daily writing, we will not explain their usage any further.

You should have seen them at least once nevertheless:

  • Floor & Ceiling Corners –⌊ ⌋ & ⌈ ⌉
  • Quine Corners or Half Brackets – ⸤ ⸥ & ⸢ ⸣
  • Double Brackets –⟦ ⟧
  • Brackets with Quills – ⁅ ⁆