Prefixes are an S3 concept that represent the path to a virtual folder. They are a way to help you visualize the concept of cloud storage and storage, given that no actual folders truly exist, and allow you to group objects by using common strings.
For example, setting a rule that applies to the /foo prefix would apply to all objects that start with /foo, such as /foo/bar, /foo/bar1/bar2, etc.
Note: A rule can only be assigned a single prefix.