| Regex operator | Meaning |
| . | Matches any single character. |
| ? | The preceding item is optional and will be matched, at most, once. |
| * | The preceding item will be matched zero or more times. |
| + | The preceding item will be matched one or more times. |
| {N} | The preceding item is matched exactly N times. |
| {N,} | The preceding item is matched N or more times. |
| {N,M} | The preceding item is matched at least N times, but not more than M times. |
| - | Represents the range if it's not first or last in a list or the ending point of a range in a list. |
| ^ | Matches the empty string at the beginning of a line; also represents the characters not in the range of a list. |
| $ | Matches the empty string at the end of a line. |
| \b | Matches the empty string at the edge of a word. |
| \B | Matches the empty string provided it's not at the edge of a word. |
| < | Match the empty string at the beginning of word. |
| > | Match the empty string at the end of word. |
| (a | b) |
| [abc] | Range (a or b or c) |
| [^abc] | NOT a or b or c |
| [a-z] | Any letter (lowercase) from a to z |
| [A-Z] | Any letter (uppercase) from a to z |
| [a-zA-Z] | Any letter (upper and lowercase) from a to z |
| [0-9] | Any digit from 0 to 9 |
A most exhaustive cheat sheet is available here