Indicates if a bucket exists and whether the requester has READ access to it.

If you make a HEAD request that's scoped to a bucket that doesn't exist, you
will get a [404 Not Found](https://docs.cloud.google.com/storage/docs/xml-api/reference-status.md.txt) status
code.

## Query string parameters

This request does not typically include query string parameters.

See [signed URL query string parameters](https://docs.cloud.google.com/storage/docs/authentication/canonical-requests.md.txt#required-query-parameters) for information on the parameters
you include when creating and using [signed URLs](https://docs.cloud.google.com/storage/docs/access-control/signed-urls.md.txt).

## Request headers

| Header | Description | Required |
|---|---|---|
| `Authorization` | The authentication string for the request. | Yes |
| `Content-Length` | The length of the request body without headers (in bytes). | No |
| `Date` | The date and time of the request. | No |
| `Host` | The URI for Cloud Storage. For more information, see [Request Endpoints](https://docs.cloud.google.com/storage/docs/request-endpoints.md.txt). | Yes |
| `x-goog-user-project` | The project to be billed for charges associated with the request. | No |

## Request body elements

This request does not include an XML document in the request body.

## Request syntax

```
HEAD / HTTP/1.1
Host: BUCKET_NAME.storage.googleapis.com
Date: DATE
Content-Length: 0
Authorization: AUTHENTICATION_STRING
```

## Response headers

The request returns standard response headers.

## Response body elements

The response does not include an XML document in the response body. Error
responses to HEAD requests also do not contain a response body.

## Example

The following sample shows a HEAD request for a bucket named `travel-maps`.

**Request**

```
HEAD / HTTP/1.1
Host: travel-maps.storage.googleapis.com
Authorization: Bearer ya29.AHES6ZRVmB7fkLtd1XTmq6mo0S1wqZZi3-Lh_s-6Uw7p8vtgSwg
```

**Response**

```
HTTP/1.1 200 OK
...
```