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+# @astrojs/lit 🔥
+
+This **[Astro integration][astro-integration]** enables server-side rendering and client-side hydration for your [Lit](https://lit.dev/) custom elements.
+
+## Installation
+
+There are two ways to add integrations to your project. Let's try the most convenient option first!
+
+### (experimental) `astro add` command
+
+Astro includes a CLI tool for adding first party integrations: `astro add`. This command will:
+1. (Optionally) Install all necessary dependencies and peer dependencies
+2. (Also optionally) Update your `astro.config.*` file to apply this integration
+
+To install `@astrojs/lit`, run the following from your project directory and follow the prompts:
+
+```sh
+# Using NPM
+npx astro add lit
+# Using Yarn
+yarn astro add lit
+# Using PNPM
+pnpx astro add lit
+```
+
+If you run into any hiccups, [feel free to log an issue on our GitHub](https://github.com/withastro/astro/issues) and try the manual installation steps below.
+
+### Install dependencies manually
+
+First, install the `@astrojs/lit` integration like so:
+
+```
+npm install @astrojs/lit
+```
+
+Most package managers will install associated peer dependencies as well. Still, if you see a "Cannot find package 'lit'" (or similar) warning when you start up Astro, you'll need to install `lit` and `@webcomponents/template-shadowroot`:
+
+```sh
+npm install lit @webcomponents/template-shadowroot
+```
+
+Now, apply this integration to your `astro.config.*` file using the `integrations` property:
+
+__astro.config.mjs__
+
+```js
+import lit from '@astrojs/lit';
+
+export default {
+  // ...
+  integrations: [lit()],
+}
+```
+
+## Getting started
+
+To use your first Lit component in Astro, head to our [UI framework documentation][astro-ui-frameworks]. This explains:
+- 📦 how framework components are loaded,
+- 💧 client-side hydration options, and
+- 🪆 opportunities to mix and nest frameworks together
+
+However, there's a key difference with Lit _custom elements_ over conventional _components_: you can use the element tag name directly.
+
+Astro needs to know which tag is associated with which component script. We expose this through exporting a `tagName` variable from the component script. It looks like this:
+
+__src/components/my-element.js__
+
+```js
+import { LitElement, html } from 'lit';
+
+export const tagName = 'my-element';
+
+class MyElement extends LitElement {
+  render() {
+    return html` <p>Hello world! From my-element</p> `;
+  }
+}
+
+customElements.define(tagName, MyElement);
+```
+
+> Note that exporting the `tagName` is __required__ if you want to use the tag name in your templates. Otherwise you can export and use the constructor, like with non custom element frameworks.
+
+In your Astro template import this component as a side-effect and use the element.
+
+__src/pages/index.astro__
+
+```astro
+---
+import '../components/my-element.js';
+---
+
+<my-element></my-element>
+```
+
+> Note that Lit requires browser globals such as `HTMLElement` and `customElements` to be present. For this reason the Lit renderer shims the server with these globals so Lit can run. You *might* run into libraries that work incorrectly because of this.
+
+### Polyfills & Hydration
+
+The renderer automatically handles adding appropriate polyfills for support in browsers that don't have Declarative Shadow DOM. The polyfill is about *1.5kB*. If the browser does support Declarative Shadow DOM then less than 250 bytes are loaded (to feature detect support).
+
+Hydration is also handled automatically. You can use the same hydration directives such as `client:load`, `client:idle` and `client:visible` as you can with other libraries that Astro supports.
+
+```astro
+---
+import '../components/my-element.js';
+---
+
+<my-element client:visible />
+```
+
+The above will only load the element's JavaScript when the user has scrolled it into view. Since it is server rendered they will not see any jank; it will load and hydrate transparently.
+
+### More documentation
+
+Check our [Astro Integration Documentation][astro-integration] for more on integrations.
+
+[astro-integration]: https://docs.astro.build/en/guides/integrations-guide/
+[astro-ui-frameworks]: https://docs.astro.build/en/core-concepts/framework-components/#using-framework-components