| Order | Expression | Description |
| 0 | [0-9] | It matches any single decimal digit from 0 through 9. |
| 1 | [0-9]+ | It matches a string of numbers. |
| 2 | [a-z] | It matches any single Letter from lower-case a through lowercase z. |
| 3 | [A-Z] | It matches any single Letter from uppercase A through uppercase Z. |
| 4 | [a-Z] | It matches any Letter from lowercase a through uppercase Z. |
| 5 | [a-Z]+ | It matches a string of Letters. |
| 6 | [0-9a-Z] | It matches any single digit or character from lowercase a through uppercase Z. |
| 7 | [^0-9] | It matches any single character except 0-9. |
| 8 | [^a-Z] | It matches any single character except a-Z. |
| 9 | [^0-9a-Z] | It matches any single character except a-Z and 0-9. |
| 10 | p+ | It matches any string containing at least one p (p can be replaced with any char). |
| 11 | p* | It matches any string containing zero or more p's (p can be replaced with any char). |
| 12 | p? | It matches any string containing zero or more p's. This is just an alternative way to use p*(p can be replaced with any char). |
| 13 | p{n} | It matches any string containing a sequence of n p's(p can be replaced with any char). |
| 14 | p{n,m} | It matches any string containing a sequence of n to m p's(n and m is a number, and m must be greater than n;p can be replaced with any char). |
| 15 | p{n,} | It matches any string containing a sequence of at least n p's(p can be replaced with any char). |
| 16 | p{,m} | It matches any string containing a sequence of at most m p's(p can be replaced with any char). |
| 17 | p$ | It matches any string with p at the end of it(p can be replaced with any char). |
| 18 | ^p | It matches any string with p at the beginning of it(p can be replaced with any char). |
| 19 | . | It matches any single char. |
| 20 | .+ | It matches any string with max length. |
| 21 | .+? | It matches any string with min length. |
| 22 | ＜b＞(.*)＜/b＞ | It matches any string enclosed within ＜b＞ and ＜/b＞. |
| 23 | p(hp)* | It matches any string containing a p followed by zero or more instances of the sequence php. |
| 24 | [[:alpha:]] | It matches any string containing alphabetic characters aA through zZ. |
| 25 | [[:digit:]] | It matches any string containing numerical digits 0 through 9. |
| 26 | [[:alnum:]] | It matches any string containing alphanumeric characters aA through zZ and 0 through 9. |
| 27 | [[:space:]] | It matches any string containing a space. |
| 28 | \s | It matches any whitespace character (space, tab, newline). |
| 29 | \S | It matches any non-whitespace character. |
| 30 | \d | It matches a digit (0-9). |
| 31 | \d+ | equal to [0-9]+. |
| 32 | \D | It matches any non-digit. |
| 33 | \w | It matches any word including "_". |
| 34 | [aeiou1236_%\$\#\.\*] | matches a single character in the given set except "\". |
| 35 | [^aeiou] | matches a single character outside the given set . |
| 36 | (x|y|z) | matches any of the alternatives specified(x,y,z can be replaced with any string. |
| 37 | \. | it matches . itself. |
| 38 | \\ | it matches \ itself. |
| 39 | \- | it matches - itself. |
| 40 | \* | it matches * itself. |
| 41 | \? | it matches ? itself. |
| 42 | \+ | it matches + itself. |
| 43 | \$ | it matches $ itself. |
| 44 | \^ | it matches ^ itself. |