# Theme Configs

Theme configs let you customize your theme. You can define theme configs by adding `themeConfig` key to the config file.

```ts
export default {
  lang: 'en-US',
  title: 'VitePress',
  description: 'Vite & Vue powered static site generator.',

  // Theme related configurations.
  themeConfig: {
    logo: '/logo.svg',
    nav: [...],
    sidebar: { ... }
  }
}
```

Here it describes the settings for the VitePress default theme. If you're using a custom theme created by others, these settings may not have any effect, or might behave differently.

## logo

- Type: `string`

Logo file to display in nav bar, right before the site title.

```ts
export default {
  themeConfig: {
    logo: '/logo.svg'
  }
}
```

## footer

- Type: `Footer`

Footer configuration. You can add a message and copyright. The footer will displayed only when the page doesn't contain sidebar due to design reason.

```ts
export default {
  themeConfig: {
    footer: {
      message: 'Released under the MIT License.',
      copyright: 'Copyright © 2019-present Evan You'
    }
  }
}
```

```ts
export interface Footer {
  message?: string
  copyright?: string
}
```

## carbonAds

- Type: `CarbonAds`

A option to display [Carbon Ads](https://www.carbonads.net/).

```ts
export default {
  themeConfig: {
    carbonAds: {
      code: 'your-carbon-code',
      placement: 'your-carbon-placement'
    }
  }
}
```

```ts
export interface CarbonAds {
  code: string,
  placement: string
}
```

Learn more in [Theme: Carbon Ads](../guide/theme-carbon-ads)