| [abx-z] | One character of: a, b, or the range x-z |
| [^abx-z] | One character except: a, b, or the range x-z |
| a|b | a or b |
| a? | Zero or one a's |
| a* | Zero or more a's |
| a+ | One or more a's |
| a{4} | Exactly 4 a's |
| a{4,8} | Between (inclusive) 4 and 8 a's |
| a{9,} | 9 or more a's |
| (...) | A capturing group |
| (?:...) | A non-capturing group |
| (?=...) | A lookahead |
| (?!...) | A negative lookahead |
| ^ | Beginning of the string |
| $ | End of the string |
| \d | A digit (same as [0-9]) |
| \D | A non-digit (same as [^0-9]) |
| \w | A word character (same as [_a-zA-Z0-9]) |
| \W | A non-word character (same as [^_a-zA-Z0-9]) |
| \s | A whitespace character |
| \S | A non-whitespace character |
| \b | A word boundary |
| \B | A non-word boundary |
| \n | A newline |
| \t | A tab |
| \cY | The control character with the hex code Y |
| \xYY | The character with the hex code YY |
| \uYYYY | The character with the hex code YYYY |
| . | Any character |
| \Y | The Y'th captured group |
