---
title: Rules language
description: Write rule expressions using the Cloudflare Rules language.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/ruleset-engine/llms.txt  
> Use this file to discover all available pages before exploring further.

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# Rules language

The Cloudflare Rules language is a flexible and intuitive specification for building rule expressions. Based on the widely known [Wireshark display filters ↗](https://www.wireshark.org/docs/wsug%5Fhtml%5Fchunked/ChWorkBuildDisplayFilterSection.html), the Rules language allows you to precisely target HTTP requests with a syntax and semantics familiar to security engineers.

Refer to the following pages for more information about the available language elements:

* [ Expressions ](https://developers.cloudflare.com/ruleset-engine/rules-language/expressions/)
* [ Operators and grouping symbols ](https://developers.cloudflare.com/ruleset-engine/rules-language/operators/)
* [ Values ](https://developers.cloudflare.com/ruleset-engine/rules-language/values/)
* [ Actions ](https://developers.cloudflare.com/ruleset-engine/rules-language/actions/)
* [ Fields ](https://developers.cloudflare.com/ruleset-engine/rules-language/fields/)
* [ Functions ](https://developers.cloudflare.com/ruleset-engine/rules-language/functions/)

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/ruleset-engine/","name":"Ruleset Engine"}},{"@type":"ListItem","position":3,"item":{"@id":"/ruleset-engine/rules-language/","name":"Rules language"}}]}
```