Rules are the building blocks of interactivity in your experience.
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GMetri uses rules in the form of simple sentences. Like\ `When polygon is clicked``,`` ``Then video should disappear`
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Rules are always of the form: **When Something Happens****, ****Then Do Something**
You can combine multiple *When Events* using `AND` or `OR` highlighted above. You can also combine multiple *Then Actions*. Click on "+Add an Action" to add *Then Actions*, Click on "Add an Event" to add *When Events*.
## Example: Viewer Rules
Using a "When Rule", you can detect when a viewer **enters a zone**.
Viewr Rules
Also, using a "Then Rule" you can make the Viewer do the following:
* **Teleport** to another scene, object, or zone.
* **Change the scene** to a different one within the experience.
* **Direct** the viewer to a specific object or element.
## More About Rules
* [shared-rules](https://docs.gmetri.com/metaverse/build/rules/shared-rules "mention")
* [how-rules-work](https://docs.gmetri.com/metaverse/build/rules/how-rules-work "mention")
* [number-variable-rules](https://docs.gmetri.com/metaverse/build/rules/number-variable-rules "mention")
* [string-variable-rules](https://docs.gmetri.com/metaverse/build/rules/string-variable-rules "mention")
* [boolean-variable-rules](https://docs.gmetri.com/metaverse/build/rules/boolean-variable-rules "mention")
## Also Read
* [string-substitution](https://docs.gmetri.com/metaverse/build/variables/string-substitution "mention")
* [zones](https://docs.gmetri.com/metaverse/build/scenes/3d-scene/zones "mention")
