<p>An Amazon S3 bucket has no directory hierarchy such as you would find in a typical computer
     file system. You can, however, create a logical hierarchy by using object key names that
     imply a folder structure. For example, instead of naming an object <code>sample.jpg</code>,
     you can name it <code>photos/2006/February/sample.jpg</code>.</p>

     <p>To get an object from such a logical hierarchy, specify the full key name for the object
     in the <code>GET</code> operation. For a virtual hosted-style request example, if you have
     the object <code>photos/2006/February/sample.jpg</code>, specify the resource as
        <code>/photos/2006/February/sample.jpg</code>. For a path-style request example, if you
     have the object <code>photos/2006/February/sample.jpg</code> in the bucket named
        <code>examplebucket</code>, specify the resource as
        <code>/examplebucket/photos/2006/February/sample.jpg</code>. For more information about
     request types, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/dev/VirtualHosting.html#VirtualHostingSpecifyBucket">HTTP Host Header Bucket Specification</a>.</p>

     <p>For more information about returning the ACL of an object, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObjectAcl.html">GetObjectAcl</a>.</p>

     <p>If the object you are retrieving is stored in the S3 Glacier or
     S3 Glacier Deep Archive storage class, or S3 Intelligent-Tiering Archive or
     S3 Intelligent-Tiering Deep Archive tiers, before you can retrieve the object you must first restore a
     copy using <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_RestoreObject.html">RestoreObject</a>. Otherwise, this action returns an
        <code>InvalidObjectStateError</code> error. For information about restoring archived
     objects, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/dev/restoring-objects.html">Restoring Archived
        Objects</a>.</p>

     <p>Encryption request headers, like <code>x-amz-server-side-encryption</code>, should not
     be sent for GET requests if your object uses server-side encryption with KMS keys (SSE-KMS)
     or server-side encryption with Amazon S3–managed encryption keys (SSE-S3). If your
     object does use these types of keys, you’ll get an HTTP 400 BadRequest error.</p>
     <p>If you encrypt an object by using server-side encryption with customer-provided
     encryption keys (SSE-C) when you store the object in Amazon S3, then when you GET the object,
     you must use the following headers:</p>
     <ul>
        <li>
           <p>x-amz-server-side-encryption-customer-algorithm</p>
        </li>
        <li>
           <p>x-amz-server-side-encryption-customer-key</p>
        </li>
        <li>
           <p>x-amz-server-side-encryption-customer-key-MD5</p>
        </li>
     </ul>
     <p>For more information about SSE-C, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/dev/ServerSideEncryptionCustomerKeys.html">Server-Side Encryption (Using
        Customer-Provided Encryption Keys)</a>.</p>

     <p>Assuming you have the relevant permission to read object tags, the response also returns the
        <code>x-amz-tagging-count</code> header that provides the count of number of tags
     associated with the object. You can use <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObjectTagging.html">GetObjectTagging</a> to retrieve
     the tag set associated with an object.</p>

     <p>
        <b>Permissions</b>
     </p>
     <p>You need the relevant read object (or version) permission for this operation. For more
     information, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/dev/using-with-s3-actions.html">Specifying Permissions
        in a Policy</a>. If the object you request does not exist, the error Amazon S3 returns
     depends on whether you also have the <code>s3:ListBucket</code> permission.</p>
     <ul>
        <li>
           <p>If you have the <code>s3:ListBucket</code> permission on the bucket, Amazon S3 will
           return an HTTP status code 404 ("no such key") error.</p>
        </li>
        <li>
           <p>If you don’t have the <code>s3:ListBucket</code> permission, Amazon S3 will return an
           HTTP status code 403 ("access denied") error.</p>
        </li>
     </ul>


     <p>
        <b>Versioning</b>
     </p>
     <p>By default, the GET action returns the current version of an object. To return a
     different version, use the <code>versionId</code> subresource.</p>

     <note>
        <ul>
           <li>
              <p>
                If you supply a <code>versionId</code>, you need the <code>s3:GetObjectVersion</code> permission to
                access a specific version of an object. If you request a specific version, you do not need to have
                the <code>s3:GetObject</code> permission.
            </p>
           </li>
           <li>
              <p>If the current version of the object is a delete marker, Amazon S3 behaves as if the
              object was deleted and includes <code>x-amz-delete-marker: true</code> in the
              response.</p>
           </li>
        </ul>
     </note>


     <p>For more information about versioning, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutBucketVersioning.html">PutBucketVersioning</a>. </p>

     <p>
        <b>Overriding Response Header Values</b>
     </p>
     <p>There are times when you want to override certain response header values in a GET
     response. For example, you might override the <code>Content-Disposition</code> response
     header value in your GET request.</p>

     <p>You can override values for a set of response headers using the following query
     parameters. These response header values are sent only on a successful request, that is,
     when status code 200 OK is returned. The set of headers you can override using these
     parameters is a subset of the headers that Amazon S3 accepts when you create an object. The
     response headers that you can override for the GET response are <code>Content-Type</code>,
        <code>Content-Language</code>, <code>Expires</code>, <code>Cache-Control</code>,
        <code>Content-Disposition</code>, and <code>Content-Encoding</code>. To override these
     header values in the GET response, you use the following request parameters.</p>

     <note>
        <p>You must sign the request, either using an Authorization header or a presigned URL,
        when using these parameters. They cannot be used with an unsigned (anonymous)
        request.</p>
     </note>
     <ul>
        <li>
           <p>
              <code>response-content-type</code>
           </p>
        </li>
        <li>
           <p>
              <code>response-content-language</code>
           </p>
        </li>
        <li>
           <p>
              <code>response-expires</code>
           </p>
        </li>
        <li>
           <p>
              <code>response-cache-control</code>
           </p>
        </li>
        <li>
           <p>
              <code>response-content-disposition</code>
           </p>
        </li>
        <li>
           <p>
              <code>response-content-encoding</code>
           </p>
        </li>
     </ul>

     <p>
        <b>Additional Considerations about Request Headers</b>
     </p>

     <p>If both of the <code>If-Match</code> and <code>If-Unmodified-Since</code> headers are
     present in the request as follows: <code>If-Match</code> condition evaluates to
        <code>true</code>, and; <code>If-Unmodified-Since</code> condition evaluates to
        <code>false</code>; then, S3 returns 200 OK and the data requested. </p>

     <p>If both of the <code>If-None-Match</code> and <code>If-Modified-Since</code> headers are
     present in the request as follows:<code> If-None-Match</code> condition evaluates to
        <code>false</code>, and; <code>If-Modified-Since</code> condition evaluates to
        <code>true</code>; then, S3 returns 304 Not Modified response code.</p>

     <p>For more information about conditional requests, see <a href="https://tools.ietf.org/html/rfc7232">RFC 7232</a>.</p>

     <p>The following operations are related to <code>GetObject</code>:</p>
     <ul>
        <li>
           <p>
              <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_ListBuckets.html">ListBuckets</a>
           </p>
        </li>
        <li>
           <p>
              <a href="https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObjectAcl.html">GetObjectAcl</a>
           </p>
        </li>
     </ul>