RegEx

^	Start of the line
$	End of the line
s	Whitespace
S	Not whitespace
?=	Lookahead
?!	Negative lookahead
?<=	Lookbehind (usually has to be constant length)
?!=	Negative lookbehind
?<!	Negative lookbehind

?	0 or 1
*	0 or more
+	1 or more
{3}	Exactly 3
{3,}	3 or more
{7,9}	Between 7 and 9, inclusive