RegExp	Description
.	Match any character except new line
x y	Match the x then y
x \| y	Match either the x or y
x *	Match the x zero or more times
x +	Match the x one or more times
x ?	Match the x zero or one times
(:? x )	Non-capturing group
( x )	Capturing group
\p{ N }	Char of the general category N
\P{ N }	Char not of the general category N
[ x ]	Character class x
[^ x ]	Character not in the class x
[ x - y ]	Character in range x..y
[\p{ N }]	Char of the general category N
[\P{ N }]	Char not of the general category N
^	Start of line assertion
$	End of line assertion
\b	Word boundary assertion
\B	Not a word boundary assertion
\d	A digit (like `[0-9]`)
\D	Not a digit (like `[^0-9]`)
\s	A whitespace (like `[\p{z}\r\n\t\f\v]`)
\S	Not a whitespace
\w	A word character (like `[A-Za-z0-9_]`)
\W	Not a word char (like `[^A-Za-z0-9_]`)
x	Character literal x, not in `^$.*+?]{}`
\ x	Character literal x in `^$.*+?]{}`
\n \r \t	New line, tabulation and other controls
[\n\r]	The same in a character class

Useful articles