> Portal Navigation:
> 
> - Append `.md` to any URL under `https://dev.wix.com/docs/` to get its markdown version.
> - Pages are either content pages (article or reference text) or menu pages (a list of links to child pages).
> - To get a menu page, truncate any URL to a parent path and append `.md` (e.g. `https://dev.wix.com/docs/sdk.md`, `https://dev.wix.com/docs/sdk/core-modules.md`).
> - Top-level index of all portals: https://dev.wix.com/docs/llms.txt
> - Full concatenated docs: https://dev.wix.com/docs/llms-full.txt

## Resource: About Site Plugins

## Article: About Site Plugins

## Article Link: https://dev.wix.com/docs/studio-two/code-your-site/build-a-custom-frontend/site-plugins/about-site-plugins.md

## Article Content:

# About Site Plugins

A [site plugin](https://dev.wix.com/docs/overview/extensions-framework/site-extensions/site-plugins.md) is a custom element that renders in a slot on a widget built by a Wix business solution, such as the Wix eCommerce [Side Cart](https://support.wix.com/en/article/customizing-the-side-cart), so you can extend that widget with your own content. A slot is a UI placeholder in the widget where a site plugin can render.

For when to use a site plugin, how slots work, and the plugin's runtime contexts and permissions, see [Site Plugins](https://dev.wix.com/docs/overview/extensions-framework/site-extensions/site-plugins.md).

## Anatomy of a site plugin

A site plugin in a Studio Two project is a configuration file, the custom element that renders in the slot, and a settings panel:

- The **custom element** is the plugin's code, a class that extends `HTMLElement`.
- The **settings panel** is a React component for the plugin's settings.
- The **configuration file** declares the plugin's ID, name, slots, tag name, and the paths to the other two files. For the full set of fields, see [Site Plugin Extension Files and Code](https://dev.wix.com/docs/site-extensions/site-plugins/site-plugin-extension-files-and-code.md).

## How site plugins are used

- You add the plugin from the **Code** tab through the **Wix Extension Builder**, which places its files in your site project and registers it.
- You choose the slot the plugin fills. Each slot belongs to a widget of a Wix business solution, such as Wix eCommerce, so the plugin can appear only on a site where that business solution is installed.
- You place the plugin in its slot in the editor, from the widget's **Plugin Market**, a panel that lists the plugins for the widget's slots. Studio Two doesn't place the plugin in its slot when you generate it.
- When the widget renders, its slot can pass data to the plugin, depending on the slot.
- From the plugin, you can call Wix APIs.

## Slots you can use in Studio Two

In a Studio Two site, you place a plugin in its slot from the editor, so the slot must be on a page that you can open in the editor, such as the Side Cart. The Side Cart is a preview of the Cart page that opens on the side of the site's pages.

The Wix eCommerce Checkout page has slots, but it isn't one of the pages you can open in the editor.

The Wix Stores product and category pages and the Wix Events pages don't have slots, although the **Wix Extension Builder** lists slots for them.

## See also

- [Add a Site Plugin Extension in Studio Two](https://dev.wix.com/docs/studio-two/code-your-site/build-a-custom-frontend/site-plugins/add-a-site-plugin-extension-in-studio-two.md)
- [Site Plugins](https://dev.wix.com/docs/overview/extensions-framework/site-extensions/site-plugins.md)
- [Site Plugin Extension Files and Code](https://dev.wix.com/docs/site-extensions/site-plugins/site-plugin-extension-files-and-code.md)