In U.S. publishing, the most common terms for these punctuation marks are as follows:

( ) *parentheses* or *parens*

[ ] *brackets* or *square brackets*

{ } *braces* or *curly brackets* or *set symbols*

< > *angle brackets*

In some math textbooks, you may also encounter these two types of brackets:

⌊ ⌋ *floor brackets*

⌈ ⌉ *ceiling brackets*

RapidTables has a page devoted to numerous mathematical symbols, including various types of brackets. I believe that the terminology reported there reflects U.S. naming conventions.

**Correction:** In a comment below, I inadvertently misstated RapidTables' description of the function of the ⌊ ⌋ and ⌈ ⌉ brackets as "rounding down" and "rounding up"; the wording that RapidTables actually uses is "rounds number to lower integer" and "rounds number to upper integer." However, tchrist (who clearly has a better grasp of the situation than I do) says in a comment below that the words "rounding up" and "rounding down" misrepresent what floor and ceiling functions do. I reproduce part of his comment here, for accuracy: "The floor and ceiling functions are not “rounding down” or “rounding up”. floor(-4.3) or ⌊ −4.3 ⌋ = −5, while ceiling(-4.3) or ⌈ −4.3 ⌉ = −4. So floor(𝑛) rounds to the largest integral value not greater than 𝑛, while ceiling(𝑛) rounds to the smallest integral value not less than 𝑛." Thanks, tchrist!

*Words Into Type*, Third Edition (1974) indicates that, in U.S. publishing 40 years ago, compositors used the term *bracket* very narrowly:

[Footnote 36] The terms *curves* and *round brackets* are never used in [U.S.] composing rooms for parentheses. The term there used is *parens*, separately designated *open paren* and *close paren*.

[Footnote 37] The word *bracket* signifies only one thing to a compositor. Asking him to use a "square" bracket is unnecessary.

The terms *open paren* and *close paren* remain common in U.S. publishing today. In view of the rise of angle brackets (especially in computer coding) and the expanded use of curly brackets, however, I doubt that any surviving compositor would deem the term *square bracket* redundant.

## Best Answer

I think

curly bracketsis the most professional name. See Wikipedia for more details.