There are special characters for creating almost any pattern.
| Character | Description |
| \w | Matches any word character (alphanumeric). |
| \W | Matches any non-word character. |
| \s | Matches any whitespace character (tab, newline, carriage return, form feed, vertical tab). |
| \S | Matches any non-whitespace character. |
| \d | Matches any numerical digit. |
| \D | Matches any character that is not a number. |
| [\b] | Matches a backspace. |
| . | Matches any character except a newline. |
| [...] | Matches any one character within the brackets. |
| [^...] | Matches any one character not within the brackets. |
| [x-y] | Matches any character in the range of x to y. |
| [^x-y] | Matches any character not in the range of x to y. |
| {x,y} | Matches the previous item at least x times but not to exceed y times. |
| {x,} | Matches the previous item at least x times. |
| {x} | Matches the previous item exactly x times. |
| ? | Matches the previous item once or not at all. |
| + | Matches the previous item at least once. |
| * | Matches the previous item any number of times or not at all. |
| | | Matches the expression to the left or the right of the | character. |
| (...) | Group everything inside parentheses into a subpattern. |
| \x | Matches the same characters that resulted from the subpattern in group number x. Groups, which are designated with parentheses, are numbered from left to right. |
| ^ | Matches the beginning of the string or beginning of a line, in multiline matches. |
| $ | Matches the end of the string or end of a line, in multiline matches. |
| \b | Matches the position between a word character and a non-word character. |
| \B | Matches the position that is not between a word character and a non-word character. |