<p>A unique, case-sensitive identifier that you provide to ensure the idempotency of the request. Idempotency ensures that an API request completes only once. With an idempotent request, if the original request completes successfully, subsequent retries with the same client token return the result from the original successful request. </p> <p>If you do not specify a client token, one is automatically generated by the Amazon Web Services SDK.</p>