description: Includes give you the power to embed external HTML files into the page.
layout: component
---
Included files are asynchronously requested using `window.fetch()`. Requests are cached, so the same file can be included multiple times, but only one request will be made.
The included content will be inserted into the `<sl-include>` element's default slot so it can be easily accessed and styled through the light DOM.
When an include file loads successfully, the `sl-load` event will be emitted. You can listen for this event to add custom loading logic to your includes.
If the request fails, the `sl-error` event will be emitted. In this case, `event.detail.status` will contain the resulting HTTP status code of the request, e.g. 404 (not found).