> 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: Add a Site Lightbox Extension

## Article: Add a Site Lightbox Extension

## Article Link: https://dev.wix.com/docs/build-apps/develop-your-app/extensions/site-extensions/site-lightboxes/add-a-site-lightbox-extension.md

## Article Content:

# Add a Site Popup Extension

A [site popup extension](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/site-extensions/about-site-extensions.md) adds a pop-up to the user's site.

<blockquote class="important">

**Important:** The content of a popup extension is composed of one of your app's [site widgets](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/site-extensions/site-widgets/about-site-widget-extensions.md). This means that before setting up a popup, your app must already have at least one widget.
</blockquote>

To create a site popup extension:

1. In the [Custom Apps page](https://manage.wix.com/account/custom-apps), select an existing app that contains site widgets.
2. In the left menu, select **Extensions**.
3. Click **Create Extension** and select **Site Popup**.
4. Enter a name for the popup. This name will appear in the site's Pages panel.
5. Configure the options for closing the popup:
   * Select whether site visitors can close it by clicking the overlay background behind the popup.
   * Select whether site visitors can close it by clicking an 'X' button. When selected, an 'X' button is added to the top right corner of the popup. When testing your popup, make sure that the 'X' does not interfere with your design.
   > **Note**: If you haven't set up a way to [close the popup in its code](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/site-extensions/about-site-extensions.md#open-and-close-a-popup-from-your-app's-code), we recommend selecting at least one of these options.
6. To define the widget that will appear in the popup, click **+ Add Widget** and select any of your app's widgets.
   > **Note**: If you include a widget that is set as [essential to your app's functionality](https://dev.wix.com/docs/build-apps/develop-your-app/extensions/site-extensions/site-widgets/about-site-widget-extensions.md#essential-widgets), deleting the popup from a site will delete the entire app.
7. Click **Save**.