All files of Alibaba Cloud OSS  are stored in buckets.  A bucket is a unit for managing the stored files. All objects must belong to a bucket.  You can set the attributes of a bucket for region and file access control and file lifecycle management. These attributes apply to all files in the bucket. Therefore, you can create different buckets to implement different management functions flexibly.

The storage space in a bucket is non-hierarchical, it lacks the features of file systems, such as directories. Therefore, all files are directly affiliated with their corresponding buckets.  However, you can group, classify, and manage relevant files by folders.