Quick Reference Chart

Character	Meaning
\	Indicates next character should not be interpreted literally if it normally is, and should be interpreted literally if it normally isn't.
^	Matches beginning of input or line.
$	Matches end of input or line.
*	Matches 0 or more instances of preceding character.
+	Matches 1 or more instances of preceding character.
?	Matches 0 or 1 instances of preceding character.
.	Matches any single character other than the newline character.
(x)	Matches x and remembers the match.
x|y	Matches either x or y.
{n}	Matches exactly n instances of preceding character (where n is an integer).
{n,}	Matches at least n instances of preceding character (where n is an integer).
{n,m}	Matches it least n and at most m instances of preceding character (where n and m are integers).
[xyz]	Matches any one of enclosed characters (specify range using hyphen, such as [0-9].
[^xyz]	Matches any character not enclosed (specify range using hyphen, such as [^0-9].
[\b]	Matches a backspace.
\b	Matches a word boundary, such as a space.
\B	Matches a nonword boundary.
\cX	Matches a control character, X.
\d	Matches a digit character (same as [0-9]).
\D	Matches a nondigit character (same as [^0-9]).
\f	Matches a form feed.
\n	Matches a line feed.
\r	Matches a carriage return.
\s	Matches a single white space character, including space, tab, form feed, and line feed (same as [\f\n\r\t\v]).
\S	Matches a single non-white-space character (same as [^\f\n\r\t\v]).
\t	Matches a tab.
\v	Matches a vertical tab.
\w	Matches any alphanumeric character, including the underscore (same as [A-Za-z0-9_]).
\W	Matches any nonword character (same as [^A-Za-z0-9_]).
\n	A reference to the last substring matching the nth parenthetical (where n is a positive integer).
\ooctal \xhex	Matches an octal or hexadecimal escape value (for embedding ASCII codes).