When listing objects and returning a delimited result (e.g. grouped by folders), this represents a group of keys with a common prefix. See https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-prefixes.html

Response Header Overrides These parameters can be used with an authenticated or presigned get object request, to override certain headers that will be sent with the response. These cannot be used with anonymous requests (although some servers like MinIO do seem to allow it). See https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObject.html

Details about an object as returned by a "list objects" operation

Metadata (standard and custom) that can be set when uploading an object.