. - Any Character Except New Line

\d - Digit (0-9)

\D - Not a Digit (0-9)

\w - Word Character (a-z, A-Z, 0-9, _)

\W - Not a Word Character

\s - Whitespace (space, tab, newline)

\S - Not Whitespace (space, tab, newline)

\b - Word Boundary

\B - Not a Word Boundary

^ - Beginning of a String

$ - End of a String

[] - Matches Characters in brackets

[^ ] - Matches Characters NOT in brackets

| - Either Or

( ) - Group

Quantifiers:

* - 0 or More

+ - 1 or More

? - 0 or One

{3} - Exact Number

{3,4} - Range of Numbers (Minimum, Maximum)

#### Sample Regexs ####

[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+