Special Characters in Regular Expressions 

\	• Precedes a literal character. <\/a> interprets the forward slash literally in the end HTML anchor tag. • Precedes an escape sequence. \n matches a newline character.
^	Matches the beginning of a string, not including the newline character. ^apple matches “apple” at the beginning of a string.
$	Matches the end of a string, not including the newline character. apple$ matches “apple” at the end of a string.
.	Matches any single character including a newline character. .apple matches any single character and then “apple”.
|	Represents a logical OR to separate alternative values. (apple|orange|banana) matches “apple”, “orange”, or “banana”.
?	Matches zero or one instance. apple (pie)? matches one or more instances of “pie”.
*	Matches zero or more instances.
+	Matches one or more instances.
( )	Encloses a sub-expression. (apple|orange|banana) matches “apple”, “orange”, or “banana”. ^(\w+) matches the beginning of a line and then one or more word characters.
[ ]	Encloses an expression that matches set of characters. [\s] matches a whitespace character or a digit. [a-z0-9] matches “a” through “z” and numbers “0” through “9”.
{ }	Encloses an expression that represents repetition. apple{3} repeats three times. apple{3,} repeats at least three times as many times as possible. apple{3, 10} repeats three times but no more than 10 times. Append a question mark to indicate repeating as few times as possible. For example, apple{3,}? repeats at least three times as few times as possible.