Character classes: . any character except newline \w \d \s word, digit, whitespace \W \D \S not word, digit, whitespace [abc] any of a, b, or c [^abc] not a, b, or c [a-g] character between a & g Anchors: ^abc$ start / end of the string \b \B word, not-word boundary Escaped characters: \. \* \\ escaped special characters \t \n \r tab, linefeed, carriage return [\b] \0 \cX backspace, null, control character \xA9 \u00A9 unicode escaped © Groups & Lookaround: (abc) capture group \1 backreference to group #1 (?:abc) non-capturing group (?=abc) positive lookahead (?!abc) negative lookahead Quantifiers & Alternation: a* a+ a? 0 or more, 1 or more, 0 or 1 a{5} a{2,} exactly five, two or more a{1,3} between one & three a+? a{2,}? match as few as possible ab|cd match ab or cd Flags: Global, Insensitive, Multiline, Unicode, stickY
