ExpressionSearches for a match to:
. Any one character. Includes: a letter, a number, a space or a symbol
\w Any word character. Includes: a - z, A - Z, 0 - 9 and underscore _
\W Any character that is NOT a word character.
\d Any character that is a digit. Includes: 0 - 9
\D Any character that is NOT a digit. 
\s A space, a carriage return or a new line 
\S Anything that is NOT a space, a carriage return or a new line
\b Looks for word boundaries, so that the string is not contained inside of another word.
^ The beginning of a string. Used so that this string inside another string with characters preceding it. 
$ The end of a string verifying that no other characters come after. Used to find the last characters in a string like .com. 
\b A space, beginning of the string, end of the string, or any other non-letter or non-number character. 
[ ] Any one of the characters contained within the brackets or contained in the range between the brackets.
Example: [abcde], [a-z], [123], [0-9]
[^ ] Any character that is NOT contained between the brackets or NOT contained within the range of character between the brackets.
| Ether one of the characters before OR after the pipe | symbol, but not both of the characters
Example: (m|n) search for m OR n
\ Used to escape any special regex symbol so as not to be interpreted as a regex character
* None or more of the preceding character, class or subpattern
Example: y* will match any string that contains zero or more occurances of the letter y
?

None of one of the preceding character, class or subpattern
Exmple: q? matches any string that contains  zero or more occurances of the letter q

+ One or more of the preceding character, class of subpattern 
Example: c+ will match any string that contains at least one or more of the letter c 
{n} An occurrence of the previous item exactly n times.
{n, } An occurrence of the previous item n times or more
{n,m} An occurrence of the previous item at least n times but not more than m times
i A Modifier - placed after the last forward slash of the regular expression
looks for lower or upper case instances of the regular expression
g A Modifier - placed after the last forward slash of the regular expression
performs a global match - finds all matches - does not stop with the first match
m A Modifier - placed after the last forward slash of the regular expression
performs a multi-line match