| $number | Substitutes the substring matched by group number. |
| ${name} | Substitutes the substring matched by a named group name. |
| $$ | Escaped '$' character in the result (replacement) string. |
| $& ($0) | Replaces with the whole matched string. |
| $+ ($&) | Substitutes the matched text to the last group captured. |
| $` | Substitutes all the matched text with every non-matched text before the match. |
| $' | Substitutes all the matched text with every non-matched text after the match. |
| $_ | Substitutes all the matched text to the entire string. |
| Note: | Italic terms means the strings are volatile (May vary depending on your regex flavor). |
