Regular expression

Regular expressions (or regex) are rules that govern which sequences of characters come up in a search.

Regular expressions are implemented in various languages, but the best-known implementation is the Perl Implementation, which has given rise to its own ecosystem of implementations called PCRE (Perl Compatible Regular Expression). On the Web, {{glossary("JavaScript")}} provides another regex implementation through the {{jsxref("RegExp")}} object.

See also

• Regular expressions on Wikipedia
• Interactive tutorial
• Visualized Regular Expression
• Writing regular expressions in JavaScript