lbrackets

Lbrackets, or left brackets, are the characters that begin a bracketed section in text, mathematics, and computer code. They form one half of a bracketing pair, with a corresponding right bracket. Left brackets come in several shapes, the most common being the round parenthesis "(", the square bracket "[", the curly brace "{", and the angle bracket "<" or its typographic variant ⟨. In addition, there are specialized left brackets used for tall or nested expressions, such as the left floor ⌊ and the left ceiling ⌈, which pair with the right floor ⌋ and right ceiling ⌉.

In mathematics, lbrackets are used to group terms and denote structure. They appear in expressions, matrices, and sets, and they help clarify order of operations. Angle brackets ⟨ and ⟩ are often used to denote inner products or sequences, while square brackets and parentheses are used for ordinary grouping and function arguments.

In computing and programming, left brackets have functional roles as well. Left parentheses start function calls and expressions, left square brackets access array elements or define lists in many languages, and left curly braces denote blocks of code in languages such as C, JavaScript, and others. The pairing with the right brackets is essential for syntactic correctness and readability.

Unicode and typography provide a wide range of left-bracket characters beyond the ASCII set, including various powerful or decorative forms for specialized notation and typesetting. In TeX and LaTeX, commands such as lbrack and rbrack denote left and right square brackets in math mode, underscoring their central role in bracketing across disciplines.

See also: brackets, braces, parentheses, typographic punctuation.