[
Opening bracket
PrintableASCII 91 | Hex 0x5B | U+005B
Opening bracket (ASCII 91) begins array subscripts in C, Java, Python, JavaScript, and most programming languages. In JSON, [ starts an array literal, and mismatched brackets are a frequent source of parse errors in hand-edited JSON. Regular expressions use [ to open a character class ([a-z], [0-9]). In Markdown, square brackets enclose link text in the [text](url) syntax. Shell globbing does not use brackets the same way as regex, which occasionally confuses developers switching contexts.
ASCII Code
Decimal
91
Hexadecimal
0x5B
Octal
133
Binary
0101 1011
URL Escape
%5B
Unicode
Code Point
U+005B
Escape
\u005b
UTF-8 Hex
0x5B
UTF-8 Binary
01011011
UTF-16
0x005B
UTF-32
0x0000005B
HTML Entities
Numeric
[
Hex
[
Named
[
How to Type
Windows Alt CodeAlt + 91
HTML Entity
[
Unicode InputU+005B
Source Code Representations
C / Java
"\u005B"CSS
\005BJavaScript
"\u005B"Perl
\x{005B}Python 2
u"\u005B"Python 3
\u005BRuby
\u{005B}Frequently Asked Questions
What is ASCII code 91?
ASCII code 91 represents the Opening bracket character. In hexadecimal it is 0x5B, in binary 0101 1011, and in octal 133. It is a printable character that appears as "[" in text.
How do I type ASCII 91 on a keyboard?
On Windows, hold Alt and type 91 on the numeric keypad. On Mac, you can use the Character Viewer (Edit > Emoji & Symbols). In HTML, use the entity [ or [.