.Any char (except \n)
\dDigit [0-9]
\wWord char [a-zA-Z0-9_]
\sWhitespace
\bWord boundary
^Start of string/line
$End of string/line
*0 or more
+1 or more
?0 or 1
{n,m}n to m times
[abc]Character class
[^abc]Negated class
(abc)Capture group
(?:abc)Non-capture group
a|bAlternation
(?=abc)Lookahead
(?!abc)Negative lookahead
(?<=a)Lookbehind