A `thumbnail` resource identifies different thumbnail image sizes associated with a resource. Please note the following characteristics of thumbnail images:

- A resource's `snippet.thumbnails` property is an object that identifies the thumbnail images available for that resource.
- A `thumbnail` resource contains a series of objects. The name of each object (`default`, `medium`, `high`, etc.) refers to the thumbnail image size.
- Different types of resources may support different thumbnail image sizes.
- Different types of resources may define different sizes for thumbnail images with the same name. For example, the `default` thumbnail image for a `video` resource is typically 120px by 90px, and the `default` thumbnail image for a `channel` resource is typically 88px by 88px.
- Resources of the same type may still have different thumbnail image sizes for certain images depending on the resolution of the original image or content uploaded to YouTube. For example, an HD video may support higher resolution thumbnails than non-HD videos.
- Each object that contains information about a thumbnail image size has a `width` property and a `height` property. However, the width and height properties may not be returned for that image.
- If an uploaded thumbnail image does not match the required dimensions, the image is resized to match the correct size without changing its aspect ratio. For standard videos, the image is not cropped, but may include black bars so that the size is correct. For YouTube Shorts, the image is cropped to a 9:16 portrait aspect ratio.

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## Methods

The API supports the following methods for `thumbnails` resources:

[set](https://developers.google.com/youtube/data/reference/rest/v3/thumbnails/set.md.txt)
:   Uploads a custom video thumbnail to YouTube and sets it for a video, including YouTube Shorts.

## Resource representation

The following JSON structure shows the format of a `thumbnails` resource:

```
{
  "default": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  },
  "medium": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  },
  "high": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  },
  "standard": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  },
  "maxres": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  },
  "shortsAspectRatio": {
    "url": string,
    "width": unsigned integer,
    "height": unsigned integer
  }
}
```

### Properties

The following table defines the properties that appear in this resource:

| Properties ||
|---|---|
| `default` | `object` The default thumbnail image. The default thumbnail for a video -- or a resource that refers to a video, such as a playlist item or search result -- is 120px wide and 90px tall. The default thumbnail for a channel is 88px wide and 88px tall. |
| `default.url` | `string` The image's URL. |
| `default.width` | `unsigned integer` The image's width. |
| `default.height` | `unsigned integer` The image's height. |
| `medium` | `object` A higher resolution version of the thumbnail image. For a video (or a resource that refers to a video), this image is 320px wide and 180px tall. For a channel, this image is 240px wide and 240px tall. |
| `medium.url` | `string` The image's URL. |
| `medium.width` | `unsigned integer` The image's width. |
| `medium.height` | `unsigned integer` The image's height. |
| `high` | `object` A high resolution version of the thumbnail image. For a video (or a resource that refers to a video), this image is 480px wide and 360px tall. For a channel, this image is 800px wide and 800px tall. |
| `high.url` | `string` The image's URL. |
| `high.width` | `unsigned integer` The image's width. |
| `high.height` | `unsigned integer` The image's height. |
| `standard` | `object` An even higher resolution version of the thumbnail image than the `high` resolution image. This image is available for some videos and other resources that refer to videos, like playlist items or search results. This image is 640px wide and 480px tall. |
| `standard.url` | `string` The image's URL. |
| `standard.width` | `unsigned integer` The image's width. |
| `standard.height` | `unsigned integer` The image's height. |
| `maxres` | `object` The highest resolution version of the thumbnail image. This image size is available for some videos and other resources that refer to videos, like playlist items or search results. This image is 1280px wide and 720px tall. |
| `maxres.url` | `string` The image's URL. |
| `maxres.width` | `unsigned integer` The image's width. |
| `maxres.height` | `unsigned integer` The image's height. |
| `shortsAspectRatio` | `object` The Shorts aspect ratio (9:16) version of the thumbnail image. This image size is available for YouTube Shorts that have a custom thumbnail set. |
| `shortsAspectRatio.url` | `string` The image's URL. |
| `shortsAspectRatio.width` | `unsigned integer` The image's width. |
| `shortsAspectRatio.height` | `unsigned integer` The image's height. |