# App Config: Basics ::: tip The config reference is incomplete since the config format may still receive further changes. For a complete reference of the current available options, refer to [config.ts](https://github.com/vuejs/vitepress/blob/45b65ce8b63bd54f345bfc3383eb2416b6769dc9/src/node/config.ts#L30-L65). ::: ## base - Type: `string` - Default: `/` The base URL the site will be deployed at. You will need to set this if you plan to deploy your site under a sub path, for example, GitHub pages. If you plan to deploy your site to `https://foo.github.io/bar/`, then you should set base to `'/bar/'`. It should always start and end with a slash. The `base` is automatically prepended to all the URLs that start with `/` in other options, so you only need to specify it once. ```js module.exports = { base: '/base/' } ``` ## lang - Type: `string` - Default: `en-US` The `lang` attribute for the site. This will render as a `` tag in the page HTML. ```js module.exports = { lang: 'en-US' } ``` ## title - Type: `string` - Default: `VitePress` Title for the site. This will be the suffix for all page titles, and displayed in the navbar. ```js module.exports = { title: 'VitePress' } ``` ## description - Type: `string` - Default: `A VitePress site` Description for the site. This will render as a `` tag in the page HTML. ```js module.exports = { description: 'A VitePress site' } ```