Major Description
This operation is useful to determine if a bucket exists and you have permission to access it. The operation returns a 200 OK if the bucket exists and you have permission to access it. Otherwise, the operation might return responses such as 404 Not Found and 403 Forbidden.
See the reference here:
https://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketHEAD.html