The Different Types of Brackets

by Craig Shrives

Brackets

Brackets are punctuation marks used in pairs. There are four types of brackets used in writing:
Type
Name
( )Parentheses or Round Brackets
[ ]Square Brackets or Box Brackets
{ }Braces or Curly Brackets
< >Angle Brackets or Chevrons

The infographic below provides a quick overview of the main uses of the different types of brackets:

types of brackets

Below is an explanation of how each type of bracket is used in writing, mathematics, and programming.

The Different Types of Brackets in Writing

Parentheses (or "Round Brackets")

These are round brackets ( ). In the US, round brackets are referred to as "parentheses." In writing, they are used:
  • (1) To enclose an afterthought or additional information. For example:
    • You are required to attend the meeting in Plymouth on Tuesday. (Avoid the rush hour if I were you.)
    • (Here, the text in the round brackets is afterthought.)
    • Andrew Sissons (the author) lived in New York until the age of 16.
    • (Here, the text in the round brackets is additional information.)
  • (2) To present a plural option with a singular one. For example:
    • Remove the screw(s) as shown.
    • (This could be one screw or more than one screw.)
Difference in Terminology
  • In the US, the term "parentheses" means round brackets.
  • In the UK, "parentheses" means any type of parenthetical punctuation (e.g., brackets, commas, dashes).
  • In the UK, "brackets" usually means round brackets.
Read more on using round brackets.

Square Brackets (or "Box Brackets")

These are square brackets [ ]. They are sometimes called "box brackets." They are used to make quoted text clearer by showing insertions by the current author. The text in the square brackets can clarify by adding an explanation or by replacing some the original text.
  • (1) Insertions that clarify by adding an explanation. For example:
    • He said: "I know he [James] was last."
    • (The text in the square brackets explains who "he" is.)
    • She wrote: "It compliments [sic] your eyes."
    • (The term "sic" (sic erat scriptum means "Thus it was written." It is used to highlight that the original author used "compliment" (instead of "complement").)
  • (2) Insertions that clarify by replacing the original text. For example:
    • He said: "I know [James] was last."
    • (This time, the text in the square brackets replaces "he," which was in the original.)
    Read more about using square brackets.

    Braces (or "Curly Brackets")

    These are braces { }. They are sometimes called "curly brackets." They are rarely used in writing, but they can be used to show list items or equal choices.
    • (1) List items. For example:
      • You will meet the family {Baron Smith-Jones, Baroness Smith-Jones, Master James, Master Simon}.
      • (The list in the braces is the entire list. It is not a sample. Do not use "e.g." or "i.e." with the list.)
    • (2) Equal choices. For example:
      • Write your drink choice {coke, lemonade, coffee, tea, green tea, water} on the ticket.

    Angle Brackets (or "Chevrons")

    These are angle brackets <>. They are sometimes called "chevrons." Angle brackets are typically used in double pairs in the format << >> or « ».

    Angle brackets are not common in English writing, but they are common in other languages (such as Spanish and Russian), where they are used as quotation marks. Here are some uses of angle brackets in English (rare):
    • (1) To show an aside thought. For example:
      • "Hello, Jonathan. How are you? «You look a mess, Jonathan.»
    • (2) To show the text is in another language. For example:
      • Tourist: Hello, friend. Where is Red Square please?
        Policeman 1: «What did he say?»
        Policeman 2: «I've no idea.»
      • (This practice is most common in comic strips.)
    • (3) To show an action or status. For example:
      • "Hello, Jonathan. How are you? «Offers a handshake but is rejected»
      • (Here, the text in the angle brackets shows an action. This practice is most common in film or play scripts.)
      • «Away from Keyboard»
      • (Here, the text in the angle brackets shows a status. Such messages are most common with online communications apps.)
    • (4) To show a data field. For example:
      • «PERSON» is cordially invited to the «TIME» show on «DATE».
      • (Data fields like these are common with mail-merge tools.)

    The Different Types of Brackets in Mathematics

    In Mathematics, brackets are usually nested like this:
    • { [ ( ) ] }
    When working through a calculation, do any calculations within the parentheses (), then the square brackets [], and then the braces {}. For example:
    Step
    Working
    Here's the sum:{[4 × (13-9)] ÷ 2} × 10
    1Do the () to get:{[4 × 4] ÷ 2} × 10
    2Do the [] to get:{16 ÷ 2} × 10
    3Do the {} to get:8 × 10
    Here's the answer:80

    The Different Types of Brackets in Programming

    In programming, brackets have specific uses. Here is a quick overview of how they are used in Javascript:
    Type
    Use
    ( )Parentheses are used after a word to show it is a function. Of note, variables are passed between functions by placing the variables inside the parentheses. In the short program below, we call the function "showMyMessage" and pass it the string "Grammar Monster," which is then assigned to the variable a. This is then shown in an alert box by Javascript's built-in alert function. Note the use of parentheses with the functions.

    function showMyMessage(a){alert(a);}
    showMyMessage("Grammar Monster")
    [ ]Square brackets are used for arrays. The short program below shows an alert box with the word "beef" and then one with the word "vegetables."

    var meal = ["beef","potatoes","vegetables"]
    alert (meal[0]);
    alert (meal[2]);
    { }Braces are most commonly used to show the scope of a function (i.e., where it starts and ends). The short program below shows alert boxes with the numbers 0 to 9. Note the use of braces for the functions.

    function countToTen(){
    for (i = 0; i < 10; i++){
    alert(i);
    } // this brace marks the end of the "for" statement
    } // this brace marks the end of the "countToTen" function
    < >Angle brackets are not used as brackets in programming. They are used as "less than" and "greater than" signs. The short program below shows an alert box if the number sent to the function "checkMyNumber" is between 3 and 7. Note the > and < signs in the "if" statement. ("&&" means AND.)

    function checkMyNumber(a){
    if (a > 2 && a < 8){alert("Yes, it's between 3 and 7.");}
    }
    Interactive Exercise
    Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

See Also

Read more about parenthetical punctuation. Using round brackets Using square brackets Read more about using brackets (parentheses). A choice of parentheses